I don't do HTML sanitization. I escape everything except [A-Za-z0-9,. ].

Attempts to sanitize HTML (or SQL...) by eliminating a set of "dangerous" inputs inevitably end up as whack-a-mole processes as people keep discovering new evil things to throw at you. The only secure solution is to escape everything except a small set of "safe" inputs -- this is analogous to the situation with packet filtering firewalls, where "default deny all" is widely accepted as the right way to do things.