From the latest adjudication report (August 2011 – pdf ) it shows just how important it is to get in writing permission from the landlord to redecorate. This should be done, and the proof kept safe.
Perhaps landlords when giving permission should ensure they give it in writing and perhaps add any specific conditions to it so that tenants are clear.
So if a tenant makes a request verbally then the landlord should issue them with a letter stating:
I give permission for redecoration of walls in these shades:
and for painting of skirting boards and woodwork in this colour:
If colours used outside this range the property must be returned to specific shade before end of tenancy.
Also from both tenant and landlord perspectives it’s advantageous to have photographic record of quality of paint work/decoration at start of tenancy. This ensures that true condition is known.