So, from the rulebook:
Spend 1 point of Device to clean up 1 patch of contact poison; the petroleum jelly may not be re-used
Can I spend one device to clean up a monster I suspect of being poisonous on contact ie. Gurtoss or giant spiders?
It’s only for cleaning up actual vasoline. So, if you happen to find a vasoline-covered thing on the monster…
While only usable only for yourself, I believe you can burn an Avoid Trap each time you touch it to not be poisoned.