Bounce rates that high mean something is extremely wrong with your site or the keywords you're advertising for. I've purposely setup some bogus ads to use as controls and I still only get around 85% bounce rate. If your site is interesting enough people will sometimes stick around even if they reach you randomly.
Niche products tend to do better with advertising, less competition.
Basically if it's a complete failure you're doing it wrong. Whether you can get a positive ROI is a different story