Wet towels on the floor, signs of snooping in your bathroom cabinet, and letting your kids run wild through your friend's house: if you’re guilty of these, you're probably a bad houseguest, even if your hosts are too polite to say so. Don’t make them run and hide the next time you show up on their doorstep. Use our tips to keep the welcome mat out each time you visit.

What’s the biggest sin a houseguest can commit? HomeAdvisor, a website that matches customers to local, pre-screened plumbers, remodelers and other service professionals, conducted a survey of 2000 Americans about the behaviors that are the most offensive. The biggest pet peeve, they learned, was with houseguests who stay indefinitely. Don't linger after you said you'd leave. Set a date for your departure and stick to it.

Another etiquette mistake: bringing extra guests along without telling your hosts beforehand. It's worse when freeloadering friends leave a big mess for the hostess to clean up. Survey respondents said guests from the millenial generation were the most likely to do this. On the flip side, they complained that baby boomers were the most likely to clean up a place without being asked. That might appeal to some homeowners, but not all. Uninvited cleaning can make people feel uncomfortable, or simply annoy them because they’d rather do chores their way.

And that medicine cabinet? The survey found that hosts really resent someone who rummages around in their personal belongings, whether it’s in the bathroom, bedroom or other area.

Another sign of thoughtless guests: smokers. The days of glamorous movie stars blowing smoke while they slink around the house are over. If you must smoke, ask if there’s an outside area or a place in the garage you can use. Take an ashtray or empty tin can with you, so you don’t drop ashes or leave cigarette butts behind.

Nobody likes undisciplined children running around either. If your kids are visiting with you, make them behave. Don’t wait until your hostess is on her last nerve.

Watch yourself around the refrigerator and the home bar. Your hosts will probably invite you to make yourself at home, and they wouldn't say it if they didn't mean it. Up to a point, that is. Use moderation, so you don't seem greedy.

Strip the sheets from the bed when you depart, and put them in a designated laundry spot or leave them neatly at the foot of the bed. Place used towels on the side of the tub, so they’re easy for the host to collect.

That’s not all, of course. Even small faux pas can loom large when you’re couch-surfing. Laurel Greatrix, a spokesperson for TripAdvisor Vacation Rentals, adds that you should check out—and follow—the house rules.

It's much the same as when you’re booking a rental. You'll want to read the property listing and traveler reviews for a home thoroughly, so you’ll know what’s allowed and expected. When you're a guest in someone’s home, it’s wise to do the same. Make sure you understand the basic guidelines. Don’t bring Fido or Fluffy along unless you've asked in advance. Don't bring extra people, either.

Keep the noise down, especially in the evening. if you’re watching TV, and your hosts head off to bed, or there are small children in the house who go to sleep early, be thoughtful and lower the volume.

If you want to make a long distance call on a land line, ask permission first, and promise to pay any charges. Then do it

Finally, let your host or hostess know how much you appreciate their hospitality. Bring a gift when you arrive, or take them out to dinner while you're there, and don't forget to write a nice a thank-you note as soon as you get home.