The worst lounge (currently) without any question is the Akwaaba lounge in ACC, used as a contract lounge by TK. Normally it's a semi-passable lounge, however due to renovations they've closed it and set up shop in a tiny nook next to it. It has no doors, no bathroom, one barely working air conditioner, extremely uncomfortable seating and a capacity of no more than 40 - 50 people. No wifi either.

The worst *A flagship lounge I've seen is the Cloud 9 lounge in ADD. Very limited seating, 3 food options and no showers (in fact, only 2 stalls in the bathroom). But hey, at least the beers are nice and cold.

*EDIT*

The lounge has finished it's renovations and reopened. It actually is quite nice now. Still no hot food options though, but the WiFi and seating are good.