Three of us were riding multiple days to the Upper P of Michigan last fall.
Woke up in the morning and one rider's back tire was flat. I mean flat... Hosed it back up with a 12 volt compressor, and rode-on.
Stopped later, and it was pretty low again. Topped it off with more 12 volt derived air.
Couple hours later, pretty flatso again after taking a break.
My chum dumped in some SLIME we had stopped and gotten. Chased the slime with some air and rode on again.
Couple HUNDRED miles later, we stopped for the night. Next morning, tire still JUST FINE.
Couple months later, TIRE STILL FINE.
It was a TUBED tire as well.
All that being said, I worked awhile this winter in the tech area of a local dealer. The tire guys sure hate it when you bring in a tire/wheel to be swapped or fixed with Slime has been in there. I have looked at it when a tire was broken down for changing and was surprised it could do anything at all, it was just like lime green Kool-Aid, but I have seen it work.
I guess I am 50-50 on it too. If it could save a day, or get you through a trip, I think it's worth a try. As long as you know it may not work at all..... no right or wrong answer me thinks.