Near St.Petersburg, FL, there is a motel called The Banyan Tree Motel which has a very picturesque man-made lake behind it - nice big Banyan tree (hence name of motel) with park benches and nice lawned banks - and into which flow drainage pipes. All very innocent looking.....until you read the signs that say 'Please do not feed the alligators!'
I jest you not. The local reptilians use the drainage pipes as their subway system to visit the lake and have a kip on the banks. Saying that, there were no instances of anybody ever having been attacked or even severely spoken to by said alligators but I still subtracted alligator watching off my list of things to do.
As for nutters, have a word with some of the locals, I'm sure they'll advise you on places that it's OK to visit and others to avoid like the plague - it always worked for me.