I have a johndoe.public@gmail.com email address that forwards everything to johndoe@gmail.com. I do the same trick you do, but I use johndoe.public+sitename@gmail.com instead.
I sometimes use mailinator too.
I sometimes use mailinator too.
I'd say "it works if you make sure that no legitimate mail will lack a +", but some sites fail horribly when there's a + in your address. (I once got stuck in a situation where the "new account" form on a site accepted the + version, but their login form (based on email address) didn't.)