e.g. During a previous train refurbishment I managed, I've had 3m down to offer advice and specify what product to use to hold down their anti-slip tread (not for any external trim - no way would even contemplate risking gluing any trim on the outside). First advice lasted a week and then it started to come off (despite bloke being adamant it would be fine) so got them in again. Second time around has been much better, but I've noticed it has started to come off a bit again now (a year later).
I'd be fine using something like that for holding on little bits of trim on the outside of the car (rubbing strakes etc) that get no lift on them, but wouldn't risk it on a big bit of trim like a spoiler. That is just my opinion/suggestion though and you may have experience on cars that suggests otherwise of course.

Do any OEM's stick spoilers on cars with adhesive only these days, or do they still bolt? Be interesting to see