What is with these sayings?

I use dear as a way of getting across that I'm not trying to be snarky but they're really going about it the wrong way. I can't believe the frickin gauche things I read on here all the time. I'm not an etiquette expert or anything but I've been to so many weddings that I know what works and what rubs me the wrong way. I don't use 'big girl pants' but I won't hesitate to tell someone to grow a pair.