Being that the usefulness of the evolved "density of friends" sense is finely tuned to trigger/not trigger when it is advantageous/not advantageous to behaviorly change (e.g. to operate in sticky 'cooperative mode' when dense enough to form a bacterial film, but stay in/revert to 'solo survivalist' mode when there aren't yet enough to mass up) I'd be surprised if some other organism weren't evolutionary primed to disrupt this optimum, perhaps by chemically signalling for 'cooperative' when it just wastes the thin poplation's time or neutralising a colony back to 'solo' when that wastes time.
(Although both effects could be tricky, with the trigger to trigger each counter-measure being clearly also detriggered by the counter-measure, unless there's a small difference in the negative biofeedback loop pathway, and then bacteria could evolve better recognition of 'fake' trigger conditions. Anyway... Still worth looking for one or the other weaponised fakeries in anti-bacteria behaviours.)
One interesting possibilty for medicinal use, occurs to me: anti-plaque mouth-spray (or even additional to standard mouth-wash action) that discombobulates the colonies of mouth bacteria out of their reveries of thinking/knowing that they should be forming a film, to help other oral hygene methods get past the whole 'stonger together' behaviour. (Just investigate the effects of fuller ingestion of the signal upon the gut biome, friend and foe alike, obviously.)
Probably alrady being looked at, but these are my initial thoughts.