OK, maybe I can help a bit here as an adhesive chemist.
Better off getting a water based contact adhesive that a solvent based one if you can. Water based contact works the same as solvented contact but with no solvent smell. Seriousley, if working in a confined space like a van, solvented adhesive may be quick, easy and cheap, but does your lungs in if you breathe it for long enough without passing out, although you will probably be quite happy about the situation for a while before you throw up
Bostik do a water based contact, although I don't work for them.
To get old solvented glue off, soaking it with thinners will work as someone said, but again the toxicity is high. I got some old solvented adhesive off the rubber cab mats in my van by using a high pressure washer and a scrubbing brush soaked in white low odour white spirit.
Not ideal but maybe a little less pongy than thinners.
Thing aboput glue is, you put it on wanting it to stick, and then when you ant to get it off a few years later guess what ? It's stuck on
