dont forget it can take 3 cleans before the frames and glass are fully cleansed
thats not totally true, or it's misleading 
let me correct what i should have said

you should always inform all new customers of the 3 cleans, you either charge for the first clean, and spend the time there to get it cleaned first time round, or do 3 fortnightly cleans before starting a monthly or 6 weekly clean, thats how i do it,