Personally I would never touch an instructor that has had a break between CPL/IR of more than 6 months. It just shouts to me they have no real inclination to become an instructor they have only done it because they haven't managed to get an airline job.
Or maybe they'd just spent £25k+ getting CPL and ME/IR and needed to work, pay off some debts/bills and save before starting the FIC. Everyone's situation is different. Not everyone can get daddy to pay for it all.