Cheers Stephen.
Another little tip is the 'Kitchen Get-Out Clause'
Basically, if you find yourself confronted by cupboards with ten years of grease build up, a manky old oven/hob and tiles that look like they were reclaimed from a Romanian orphanage. Make out like you are happy to 'attempt' to clean them, but tell the client that they will have to sign your disclaimer - for Health & Safety reasons.
This usually puts the fear of God into them. They will ask you why, and you tell them politely that food preparation and storage areas (cooker, cuboards and tiles) in this sort of condition cannot be cleaned to the required insurance standards.
If you are lucky, they will tell you to leave them, as they are being replaced anyway. If you are slightly lucky, they will say, have a go at them anyway and we will get them replaced later.
If you are unlucky, they will say, just clean them, that's what I am paying you for! In which case you have still lost nothing. But the client is less likely to be 'picky' later when everything is not gleaming like new - because you have pre-warned him.
IMO