Many many times my checked luggage comes out from the conveyor belt with black goo on them. It can be just some traces or quite a lot of it. The goo is very sticky and greasy so it ends up dirtying my clothes when I pick up the suitcases. Here is one from today:
What is that stuff? More importantly, how do I get rid of it effectively?
Wiping, even with a wet towel or paper seems to do very little and scrubbing eventually reduces it but is rather labor intensive, so perhaps I am not doing the right thing. What product should make cleaning this off easier? With what type of implement, sponge, brush, etc?