Stinking cloud makes people nauseated. Take a look at what nauseated means:
Quote Originally Posted by SRD
Nauseated creatures are unable to attack, cast spells, concentrate on spells, or do anything else requiring attention. The only action such a character can take is a single move action per turn.
And the effect persists until 2 to 5 rounds after it gets out of the cloud.

So basically they're unable to hurt you or your allies, and they're reduced in speed if they try to get away (since they can't double move and can't run).