I have my Gmail account as a secondary, occasionally used address, and looking at it right now, of the 23 messages it displays "above the fold" in my inbox, 7 are spam.

Currently I don't see any false-positives in the Gmail 'spam' folder, but in the past, I've even seen legitimate messages from Google's own lists there (!).

It's not that my spam filters elsewhere are any better. But, at least they don't cause me to lose forever false positives that I neglect to notice within 30 days. And, there is a definite correlation between how much spam you get and how many places your naked address appears. So if you ever review your spam folder for false positives, that process is easier if you've bee protective of your address (and thus get less spam).