1. It turns out that legality is not the only standard of behavior required in civilized circles. If pointing out that you have broken no laws is all it takes for your circle of acquaintance to approve of your behavior, you need a better circle of acquaintance. This is true of presidential candidates, of Harry Potter RPGers, and of any other circle you care to name: it being legal to do something does not make it kind, tasteful, interesting, or a dozen other things that a person might wish it to be.
2. Until nanotechnology progresses further than it has to date, neither soaps nor linens are traps for the young or unwary guest, nor should they be treated as such. If you don't want someone washing their hands with something, don't put it in a soap dish by the sink. If you don't want someone drying their hands on something, don't hang it on a towel bar in the bathroom or set it on the bathroom counter conveniently close by if guests are on their way. If you suspect that you have left something unsuitable in the bathroom because your guests have caught you unawares, for heaven's sake dart in and check.
3. If someone is clinging to someone else's arm in a public place, please consider that she may not be doing it for affection's sake, and do not attempt to bully her into letting go. Your failure condition if you navigate around her is that you may have given leeway to someone who is fluttery with new romance: not necessary, certainly, but not catastrophic. Whereas your failure condition if you attempt to bull through her is that you may cause great inconvenience and further suffering to someone for whom walking around in an ordinary fashion is already more difficult than she would like it to be; anticipation of this problem may keep her from useful or enjoyable activities when she's having a difficult day. If you feel the need, you may glare discouragingly in case she's doing it for fun, because by this point she does not give the proverbial rodent's hindquarters what you think as long as you don't try to knock her down.