I am certain that Google sells their email addresses to the worst types of spammers. A couple of years ago I got a Google email account, but I never posted the info to a web site, gave it to anyone else, or sent an email from it. Despite this, I got roughly 50 pieces of spam email a day, including the standard Viagra, Rolex lookalike watches, Nigerian prince scams, refinance your home, etc. There’s no way anyone could have gotten this email address except from Google.
I get less spam with my google mail than my main email...fwiw.