For regular cleaning I've mentioned cleaning ovens 0 times on all bids since 1998 and less than 5 people have ever asked about it. When they did ask about it I told them we did not clean ovens..... they were more than ok with that and no one ever said another word about it. Oven take up too much time. Time is money and unless you charge $75 to clean an oven, just think of the money you could make cleaning another house in that same time. Yeah I know.... it only takes 15 minutes..... which leads in to all kinds of hassle and 1.25 hours later you are finished.
I always offer gloves to new people and they use them for a day or 2 and then decide it's too much hassle to use them. It's opposite with knee pads, people think they don't look cool with knee pads on and then I purposely make them wash a large floor on hands & knees.... next thing ya know.... they are asking for those knee pads. lol
I really hate referrals..... I have given discounts and I've not given discounts. I'd say that would be your call. If you like referrals and the hassle that goes with them, give a discount. I don't have time for it so I don't give any type of discounts these days.