What I do to combat things like this is preemptively block them whenever possible. For instance, if I get a PITA buyer that asks a lot of stupid, dumb questions that are already covered in my listings, they go straight on my block list. Oh, I'll go ahead and take time to answer their questions (AGAIN) alright, but they're not going to be able to buy from me...at least on ebay. I'm not sure if etsy will allow you to block buyers.
Then they get a rude awakening if/when they ever decide to stop with the tire kicking and go ahead and actually BUY something...they can't. At that point, they will send me a plaintive message and that's when I direct them to my website.
Works great for me.
Oh, and I also don't give away my work for almost nothing. I price it accordingly and that keeps out the riff-raff for the most part. There is the occasional PITA customer still, but not as many as when I sold cheaper items. I don't do that anymore and now I don't have as many bad customers.