My chain and cogs always look very dirty as the oil attracts dirt. It is a constant problem as you can't fully avoid stains on your trousers and hands. Also, that looks ugly and I believe it wears the chain and the cassette as the particles stuck on chain act as abrasive.
Before I used to think that was unavoidable, however, I noticed that on some bikes the chain and cogs are shiny clean. Is that because their owners clean the chain daily (because one day in enough for a chain to turn black after full cleaning) or because they use different lubrication solutions?
I read about teflon-based lubricants, are they really much better than a "traditional oil"? Also, these bikes with shiny chains were always single-speed bikes - does that mean geared system experience more traction and should be traditionally oiled?