One of the symptoms of a blown head gasket for a Toyota Camry is excessive steam or coolant coming from the tailpipe. Engine oil mixing with the coolant and a miss in the engine are also symptoms of a blown head gasket.
I needed to change the oil pan on my Camry and couldn't get a gasket at any of the local dsicount shops. I called the nearest Toyota dealer and the service guy told me that he doesn't replace the gasket. Instead he uses RTV silicon, I did the same and haven't had a problem.