WoW slimes are just as harmless as any other creature.
Noteworthy exeptions:
Gnomeregan slimes leave a 150dps poison cloud after they die.
AQ20 slimes are NOT to meleed by anybody exept the tank.
Viscidus should not be attempted without the whole raid having 315NR, even at 70.
About DF slimes:
Perhaps we should have degrees of corrosiveness. 2 for example takes a week or so to eat an average weapon where 5 can devour anything simply by bumping into it.
0 Things stuck in this are stuck untill somebody gets them out. Unlucky adventurers will most likely starve.
1 Slowly desintegrates content over the course of years.
2 Desintegrates at a moderate pace.
3 Semi corrosive. Damages armor with wrestling holds etc.
4 Destroys armor at a fast pace and causes considerable flesh damage.
5 Highly corrosive. Capable of damaging armor and flesh alike simply by getting in contact with them.
6 Coming in contact with this has the result of a bucket of sulphuric acid being poured over your adventurer.
I think it would be hilarious to have a chasm where you put alot of things in, and one day a 0 corrosiveness slime comes out with each of those items stuck in its head.
Once wizards are in, realy evil ones may deploy highly corrosive slimes to melt themselves through the rock as a type of miners.
Or, you find several unnaturaly smoothed tunnels going through your fresh fort. But there are no legends of anything living here. Only a small goblin caravan that disappeared without a trace. The only clues are two words carved in the rock, that in goblin tongue read "it burns". It looks like something tried to erase them by pouring acid over it, but failed to remove them completely.
Would you dare to build a fort there?