I've only used it a couple of times but:
The engine does not smoke.
The oil is not over filled.
The oil does not smell like gas.
I haven't run it enough to foul the plug.
From what I can tell it looks like about a tablespoon of oil will leak out of the bottom of the valve cover over two weeks.
The engine does not make a hissing sound.
I don't believe I have a head gasket problem. I think someone miss diagnosed the oil leak at the valve cover. I'm going to do the compression test in the morning and not worry about it if the compression is at 100-120.