Shaun,
it will always depend on who your target market clients are. If its carpeted the whole house from Carpetright for £150.00, then they may not be so worried about the clean but are geared to cost. If you have a prospective client who has spent £5000-£15,00 on carpeting its another thing entirely. They may want answers as to what you are going to do, how long wil it be to dry, what is your experience etc, so it is essential to Audit
It really applies an awful lot to what Ken says in how you conduct yourself in the Audit.