Asking for upvote is against the reddiquette (the post could be moderated because of that)
This applies only to Reddit, I guess?He is right:
In regard to voting
Send out IMs, tweets, or any other message asking people to vote for your submission or comply when other people ask you. This will result in a ban from the admins. Your submission should get points for being good, not because the submitter is part of a voting clique.
Source:
http://www.reddit.com/wiki/reddiquette