Grayorm, the guy i would say was in his late 50s. People don't realise painting and decorating is a skilled trade . Just buy some brushes and your off. You see it loads of times on the TV shows where some home owner is having a go at the painting, but never having a go at the plumbing or electrics. I always say 50% prepping and 50% painting.
Doorframe, get yourself down to specsavers. I could of uploaded more photo's of the job, but as my boy had to do it for me and it was late and at 13 he had to go to bed. What you see on the round mirror picture is a channel cut for the towel radiator cable, and filled but was never sanded, the chap just painted over it i don't think he had any sandpaper in his kit. On new or old plaster i would always put on the first coat of paint and rub down any marks on the plaster before the final coat. As most decorators are the last person on a job surely they are the man who will do as you say "somebody else's making good" within reason, as if a decorator does not spend the time doing the prepping no way will he achieve a good finish.