hairline cracks and skimming on top of live plaster

[paul76]

Hi Guys,

I am a complete diy novice. My misses and I bought an old house about a year ago and have done it up to a nice standard (well the builder has anyway!!) We cut corners a bit on some walls by not plastering, just painting over them, but now regret it and want them plastered as when daylight shines on them they are full of lumps and dart type holes. Can a plasterer just skim over the walls so they are flat or will he need to cut out the bits of live plaster then skim??? Also some of the walls that have been plastered and skimmed have slight hairline cracks on them is this the plaster cracking of the paint?
Many thanks for any help here!!!

[chancer]

overskims provide a good cosmetic touch up,but the background needs to be solid,contact a plasterer general builders dont have what it takes,use a pro!