Groove Shark is a search engine, yeah, in that it indexes free range MP3s and helps searchers get to them. But it never exposes the remote URLs, much less the originating web page.
As far as a searcher is concerned the MP3 is hosted by groove shark. When somebody hosts an MP3 they almost always want to be acknowledged, and more often than not they’re doing it to generate page views as much as plays. For grooveshark to sabotage their goals is bad faith.
Why be rude when you can so easily avoid it? How cynical do you have to be to care that little?
Seeqpod also made it hard for searchers to leave their site, but at least they gave attribution to their source hosts by showing the remote URL.