I only recently ( jamuary) started riding again after many many years, and am commuting. So I thought, hey I will slime the tires to make it so I don't get flats. I now regret that decision.
so I slimed my tubes, and it is a hassle, even though I keep the valve up high when checking ( between 11 and 1 on a clock), , at times, it squirts out on me, or my gauge or my air chuck or the side of the rim.

But yesterday, b4 riding off to town, I went to check the air pressure. Got the squirt,
But worse than that, it kind of made the valve core stick and it let out a bunch of air. only after hitting a couple of times with my gauge did it finally seal. with all the extra air coming out, so did slime and made a mess
luckily I was at home with my compressor
but now Im gonna be reluctant to check my tires away from the house.

I guess I know my next bicycle part purchase. new tubes that wont get slimed.
was gonna phase em out anyway, because of the mess they would make if I ever got a flat that the slime did not seal, and I was on the side of the road trying to install a spare tube with the mess. Running thorn resistant tubes and Kevlar or the like tires, I should be ok anyway

so if your thinking of adding slime, and doing a search and come across this thread, its just another thing to keep in your mind when making your decision.