People on local groups demanding the name of a joiner who can hang three doors preferably today or tomorrow or a painter and decorator who can paint their whole downstairs by the end of the week. Fair enough if someone has let them down but lets be honest, anyone half decent isn't going to be available at the drop of a hat!
I once mistake of asking for recommendations for a gardener to come and prune a few bushes in my mum's back garden. Everyone raved about this guy so he came round, gave a reasonable quote, showed us pics etc. Then on the day he did the work, he literally took a chainsaw to some really delicate plants, lopped all the branches off the very new tree leaving a stump then announced he had another job and had to leave! He obviously didn't have a clue what he was doing. My mum was so stunned she didn't know what to say to him. She paid him because to be honest, he looked like he'd come and let your tyres down if you didn't, but I'd never go off a Facebook recommendation again!