I have my own email server with a wildcard address (I still use gmail for anything that's actually important). I put certain addresses in shady forms a few times. I get a couple of spam messages per day to those addresses - always the same spam few spam campaigns. One is offering to sell me electric bicycles or partner with me to sell electric bicycles (didn't really pay attention) and more recently I started getting business proposal advance fee spam. The volume is pretty manageable and if I wanted, a pretty simple filter tuned for the spam I actually get would catch all of it and no ham.

I got spam to postmaster once for some reason. That's a nice way to make admins aware of your spam campaign.

Spam is presumably more of a problem when you're more well-known and you don't have the option to control your own filters.