AFTER SPENDING the night at one of the major hotel chains recently and finding an unwelcome surprise behind a chair in the corner, I realize the true meaning of the term "pet peeve." It means I'm peeved at the way many hotels are loosening their policies about pets. Now, hold on, animal lovers. I love my dog. I've loved all five cats that I rescued and cared for. And I love that more doors are opening to you and your pet. I just don't want to walk in after you and step in something. According to a recent poll, more than 29 million Americans traveled with pets during the last three years. That figure is likely to have climbed this summer, as economic stress has made people vacation closer to home - meaning they will drive rather than fly, and are more likely to bring along a dog or cat.