I'm terrified of even using the offline paper wallet generators that various coins have. Would never use anything online to generate private keys, especially not someone else's site where they can just log every generated key.

Tough lesson for folks to learn but I feel like everyone needs to learn it once or twice. I've lost my keys in the past, thankfully with very few coins in them, but that stung enough that I'm now super paranoid about security and backups.