For me it would be cleanliness, clarity and respect.
CLEANLINESS - No cheesy cocks, shitty arses. smelly armpits, mouldy teeth or bad breath. No open fucking cuts either and no cold sores or the like. I'd list everything I did and restate the ones that are most often lied about for clarity in my profile, something like
CLARITY - "Yes when I say I do DT I mean I will take the full length of your cock into my mouth and as far down my throat as is necessary to get balls deep"
"Yes you can cum anywhere on me with the only exception being not on or in my bare cunt or arsehole"
"Yes I do allow you to film the session, whatever you like, however many cameras or views you want included in the fee. Personal use only!"
"If you have any doubt about the service I provide, ask in advance with full details of exactly what you want. It's no trouble for me at all and I will get back to you asap"
RESPECT - I'm a person offering you a service and will treat you as the most important person in the world during your time with me. Likewise I expect that you will treat me as well as anyone else who you might take a service from. Unless you're a cunt of course in which case I expect you to treat me as well as any non-cunt would