I've been in this situation as well. I bought a with a replaced odometer. The odometer was replaced by the service department of the dealership and according to the sales guy, the car had 10,000 miles more than what the odometer listed.
I took his word on it, as well as the service department, and later ran into a snafu trying to sell the car. Basically, nobody wanted to touch the thing. I was getting offers of $3,000-$5,000 less than what I *SHOULD* have gotten for the car, simply because they didn't like the fact that incorrect odometer setting showed up on the title.
I did some further investigations work on the car, and it's service history, and found out that the 10k miles was just a number that the dealership pulled out of thin air. Somebody had just penciled in 10,000 miles on a service paper and that's what they assumed the difference was. It could have been 10,000 miles. It could have been 50,000 miles. I'll never no.
Car is long behind me, and I'll never put myself in that situation again.
So, to make a long story short, it WILL affect his ability to resell the car.