Terry Butcher's side never seriously troubled injury-ravaged Rochdale with their route one football and it looked like being a deserved win for Keith Hill's battlers until Poole produced a spectacular 88th-minute volley totally out of keeping with what his side had previously produced.
The hosts were slow out of the blocks, but after the first 10 minutes took control of the game with Adam Rundle, Ben Muirhead and Glenn Murray all forcing saves out of Brentford keeper Simon Brown.
A minute after the restart Murray was desperately unlucky to see his header from a Muirhead free-kick rebound off the crossbar and cleared to safety.
On 63 minutes Murray put his side in front. Following a foul on the right-hand side Rundle produced an inswinging delivery which Murray glanced home from virtually under the crossbar.
Murray later went close to doubling his side's lead with an audacious volley, and skipper Gary Jones and Rundle both forced saves out of the busy Bees keeper Brown as the home side took control and pressed for a deserved second goal.
But Brentford nicked a late point when, with just 90 seconds remaining, Poole chested the ball down some 30 yards from goal before producing a stunning effort that found the net via the inside of the upright to give his side an undeserved share of the points.