Be very cautious and very wary on some of the "donation" subreddits. After investigating, it has become clear to me that some are designed to lure in poor people, so that they can ask for help, and then be ridiculed and harassed in the comments.
So i'm not saying don't use them, just saying be wary and be cautious and be ready for abusive replies. This way you're not as surprised and shocked when hit with evil comments.