Edit: I've been asked to make this more explicit. How about: If you do this you will get banned.

Don't assume that those upvotes are counted. It's a cat and mouse game. We eat a lot of mice.

If you or anyone suspects that a post has made HN's front page because of vote manipulation, you should let us know at hn@ycombinator.com so we can investigate. We have years of experience with this data.

I'd never say it never works, because we don't know what we don't know. But I can tell you that many people who've used that spam service have gotten their posts buried, their accounts banned, and their sites blacklisted.