not fit 

Newfoundland term to describe something exceptionally bad.

Her apple pie was not fit for human consumption.

not fit by Goofy Newfie August 15, 2018

Not a good fit 

Passive agressive understatement used when rejecting a job candidate, firing a worker or breaking up with a spouse, girlfriend or boyfriend. Very useful if you want to appear indifferent to the strong emotions and upset of the person on the receiving end of the negative information.

"You have been a valuable employee for the last 32 years but unfortunately, in the current conditions, you are not a good fit."

"I really want to thank you for 31 years of marriage and 12 children but at this point I think we are not a good fit anymore."

Not a good fit by Bad fit September 19, 2009