AT on... Houseguests Behaving Badly

Yesterday, we touched on the fun of hosting with the post AT on... My House is Your House. We love houseguests. Maybe we New Yorkers deal with more of them than most because of the city's expensive hotels and non-stop attractions. After having so many house guest over the years, we've certainly had our share of terrible ones who have made us swear we'll never host another:

We've dealt with furniture breakers, candy-wrapper droppers, couch potatoes, trip extenders, and the old faithful: loud snorers. What about you, AT readers? What are the worst house guest habits you've run into?