I rented a 4 seater once, was within W&B limits and only just managed to clear the boundry fence with the stall warning blaring. That aircraft certainly wasn't.
Had a similar experience on an old tired PA28, except I rejected the takeoff as it was so sluggish in accelerating.
Went back to the club, went through the W&B with the CFI, he agreed we were were 50lbs below gross.
CFI was very decent about it and refused to charge me for the Hobbs time, as he said good airmanship lead to the reject and he wanted to encourage safe flying.