My last one accidentally mixed a bag of slc instead of plasterboard adhesive,... no even the same colour!! (15 quid down the drain) i then noticed he was not the best with a measuring tape, after giving him dimensions to cut plasterboard he just couldnt get it!! ... but, ask him to do all the dirty stuff like wash down and general graft he was good!... Ive now got him to a stage where he can grout so happy with his progress!