Flat tires and Green Slime

anybody use green slime or fix a flat in a can?
I remember using the fix a flat years ago and then needed to change the tire and it was a nasty sticky mess trying to clean the rim, once I took the old tire off.
the guy at the auto parts store mentioned that this newer green slime is supposed to be a bit neater, I don't see how?
I was thinking of trying an alternative till I get time to possibly putting some tubes in.
comments?