Name: afdssdf email: fsdass@dfafd.com password:fsdssd
How many times have I filled forms out like that? Probably over 10,000. I also use my fake facebook account almost as much as my real one.
No, those are just random. If I find I actually want an account, I'll log-out and sign up with a real e-mail/password. (It's very rare.)
Most sites that require e-mail I will just leave an never come back. If it looks SUPER useful or amazing I'll go to the trouble of getting a disposable e-mail account.