Thanks for the replies guys. I wasn't really asking for advice,


I was more just curious if anyone else gets a significant number of vehicles through their doors that are pre-sale prep jobs.
As for the question about whether or not a higher price is realized by detailing a given car... that was hypothetical due to the fact that you can't sell the exact same car at the same time twice with one being freshly detailed and the other not. It just isn't possible.
Regarding what I charge... exactly the same as I would charge for the same work on a car that's not being sold. In fact, I'm less apt to negotiate the price due to the fact that in my mind, I firmly believe the car WILL sell for more BECAUSE of the work I'm doing which translates to more $$ for the seller as a direct result of my efforts.
If I do a car for, let's say $200, and the owner makes an extra $1,000 or more because of it and I don't charge said customer correctly for the work I've done, then I've done the customer a favor which probably isn't going to be reciprocated. It's not like he's going to stop by my house right after he sells the car and toss me a big fat tip.
The only piece of evidence that leads me to believe a detailed car sells for more money is what I've heard customers tell me and hearing it from a referral that "Joe X said you did his car and he got a lot more money for it. How much will you charge me to do mine?"
Now, there might be truth to that and it might just be that the seller believes the car is worth more and decides to stand firm on his price rather than believing the perceived value is actually less (for the not detailed version of the car) and therefore drops his price just to get rid of it.