The black goo is a good sign that the engine is getting lubrication all of the way through the engine.  The only oil the engine gets, is what is put in the gasoline.  The oil  you pour in the side of the engine only lubricates the transmission.

No smoke or no goo may be a sign of lack of lubrication unless your engine always runs at full throttle and high RPM. 

A two stroke engine running 15:1 fuel to oil ratio when running at sustained high RPM and full throttle will make very little smoke and no goo.  The inside of the silencer will be dry and almost soot free after a hard dyno session.