email submits question

Lately I've seen lots of methods here and there about email submits. Most of them end up in deceiving the user into submitting their email using methods that promise them something in return such as iphones, TV's etc by spamming in social media or craigslist. Don't get me wrong I don't particularly care about the users but those email are mostly useless(right?). So my main question is what percentage is likely to be shaved.