Don't see why they would be. Except if feeding fish which can disrupt the normal echo system and food chain, seal costumes wearing dead fish are seldomly the target of attacks. Sharks are more attracted by easy prays on the surface.
Saying that I'm am sure there are always a couple of idiots who probably mistake sharks for dolphins and think it would be cool to pat them on the chin (any Russian divers in Sharm?...). I've got no objection to that as it would probably fit nicely with Darwin's theory.

Oy vey....

http://2.bp.blogspot.com/_xCZXXM23n7...ind-divers.jpg

I'd have a heart attack on the spot.

Thoughts from scientists are that people splashing around on the surface are mistaken for dying fish by sharks and also surfers and snorkelers in black wetsuits are often mistaken for seals. So my point is that if you are splashing around on top of the water, especially in a wetsuit, that makes you a target. Can't say I've ever mistaken a dolphin for a shark though I have crapped my dacks (that's for you Dean) when at the beach and seen a fin, only to realise quickly that it's a dolphins fin.

Very true. If you ever go diving, always make sure there are one or two snorkeler nearby.