Americans are known to make more fashion faux pas than other travelers — and I’m not just talking about flip-flops and cargo shorts (though those are pretty bad). Making certain fashion mistakes abroad can mean disrespecting cultural norms, offending locals, and at best, making it obvious to everyone that you’re a tourist who can be taken advantage of.

Dressing badly on vacation is usually done out of blissful ignorance rather than bad intentions. Knowing these common travel-outfit mistakes could keep even the most unfashionable world traveler in check.

Under-dressing

Americans often dress more casually than people do in most other parts of the world. That habit can come off as a sign of disrespect, or even prevent you from being allowed into certain places. And it’s not just wearing sandals or lacking a suit jacket that you have to worry about.

On a recent business trip, one member of my group was asked to leave the rooftop restaurant we were all excited to see because he was breaking the dress code with his khaki shorts and Converse sneakers. We all had to leave, and I’m sure he learned his lesson about dressing for a night out in Europe. Most European cultures expect at least non-tennis shoes and long pants for men in more upscale restaurants.

Shoes that are just plain terrible

Nothing screams “tourist” more than a clunky pair of running sneakers paired with jeans in the name of comfort. You don’t need to look like you’re heading to the gym in order to save your feet from walking. This will of course vary from person to person depending on style preference and perhaps medical need — but lightweight shoes with a little bit of support usually go a long way. I prefer to stick to basics for my travel shoes. Classic, lightweight options like slip-on loafers or ankle boots will get the most use with an array of clothes, and can be transformed with the addition of simple drugstore insoles of your choosing if you want some extra cushion.

In fall or winter a warm pair of sleek Chelsea boots work for both men and women, and can transition from day to night. For warmer months, find a breathable slip-on like Allbirds loungers or Suavs (both also unisex) to avoid having bare feet on the plane. Sandals are packable: Throw a soft yet stylish pair like Sanuk’s Yoga Dawn TX sandals, which have yoga-mat insoles, into your suitcase.

Flip-flops

Flip-flops are not shoes. Flip-flops are a travel tool that you should only pack in your beach bag for the walk from the hotel to the sand — or in your suitcase’s laundry compartment for use in grimy hostel or spa showers.

For hygiene’s sake, don’t be that person in the airport security line or on the plane wearing flip-flops. For safety’s sake, don’t wear them walking around unfamiliar city streets. They’re $6 on Amazon for a reason: They shouldn’t be worn in public.

Shorts on the plane

To me, this fashion mistake is more of a comfort issue than anything else: Aren’t people who wear shorts on the plane freezing? Plane cabins are typically chilly, so covering up at least to the shins is a good idea. It might be hot outside the airport, but being comfortable on the plane should take priority, especially for long flights. Relaxed pants that breathe but will still cover you, like Everlane’s GoWeave Easy Pant, are as unrestrictive as shorts.

To airlines, however, shorts are sometimes a modesty issue. There have been instances of women being told to cover up or change into pants before getting on the plane. “The gate and on board crew discussed the customer’s clothing and determined that the burlesque shorts may offend other families on the flight,” JetBlue said in 2016 of asking a customer to change out of her shorts before her flight. “While the customer was not denied boarding, the crew members politely asked if she could change.”

It’s hard to imagine a man being asked to change his shorts, unless maybe he was traveling in first or business class — but maybe a no-shorts dress code across the board would be appropriate for plane travel.

Revealing clothing

Women visiting the Middle East are typically expected to be moderately covered, from their knees up to their shoulders. If you’re visiting during warmer weather then opt for light material, like linen pants you can dress up. A pashmina scarf is also a must-have to cover up before entering religious sites that might not allow you in otherwise. It’s a fashion mistake that could definitely ruin your sightseeing plans.

But it’s important to note that there are plenty of countries across the globe that also scrutinize certain types of revealing clothing. Buddhist cultures as well as Buddhist and Hindu temples and Christian churches typically expect women to cover up, and the shorter shorts that are widely accepted in the U.S. might not be a good idea in more traditional and/or religious parts of Europe, South America, Africa and beyond.

In heavily Catholic Spain, wearing shorts or short skirts on certain holy days, like Easter and during week-long Semana Santa festivities, is considered disrespectful. And before the temperature rises to a reasonable point, even open-toe sandals or men’s tank tops can be considered uncouth. Learning this the hard way myself when I lived and studied in the south of Spain, I put my summer clothing back into my closet until the forecast hit a consistent range of mid-80s Fahrenheit. Make sure you pack at least one back-up option, like longer shorts for women and collared short-sleeve shirts for men.

Obnoxious T-shirts

It’s a good idea to leave shirts with political slogans, designer logos or even sports team names at home if you don’t want to be approached about them. Arguing about politics and other controversial topics like religion, money and sports rivalries might be more culturally acceptable than you’d think in your destination, and wearing your opinions on your chest could make you a target for those who want to air some grievances. Plus, your travel photos will look better without huge logos or letters distracting from the scenic background.

Over-activewear

Athleisure can be a cool and comfortable way to fly — but suiting up in activewear for a day out on the town can be a good way to be pegged as an ugly American. Leave the hoodie and running shoes in the hotel room and opt instead for classic staples made from high-performance material.

A stylish yet waterproof jacket like Ralph Lauren’s Anorak Softshell (my personal favorite travel coat for its hidden hood and huge pockets) is an investment you’ll wear everywhere and can layer for different types of weather. For men, the Lauren by Ralph Lauren Men’s Water Repellant Raincoat has a similarly concealed hood in its outer shell, and is fully lined with cotton. And instead of track pants and running shoes, comfortable travel jeans and a streamlined sneaker that’s and water-resistant, like Mark Nason Riders, are just as lightweight and cozy.

Backpacks

Unless you’re commuting to class or work, there’s no reason any grown adult should be toting around a huge backpack on an average day out. Travel backpacks in particular can get huge and become a hassle for everyone around you, especially if you’re taking busy public transit or heading to a crowded tourist attraction.

Stash your travel backpack somewhere, anywhere, whether it’s at a hotel front desk for a decent tip or in an airport locker for a small fee. A small cross-body purse or a belt bag that embraces the fanny pack trend can fit all your necessities, and will be a lot more secure when it comes to pickpockets. Museums and other sites usually won’t let you in with a big bag anyway, so you could actually be missing out on some must-see stops if you make this fashion mistake.