Do you think they'll get much business? Location,location,location is key in any business. Condition of vehicles , price , and terms of warranty also important. I would guess that most of the machines are sold in "as is " condition with no warranty implied, also no responsibility for poor workmanship.
Are they registered motorcycle repair/inspection stations? Is the machine safe? Who knows, I've seen professional mechanics that take shortcuts all the time, I've seen some that are so anal that what ever it is, it's gonna take some time.
I would guess that they'd do alright if the machines are decent, priced right, and sold as is. You don't think a big dealership will offer any better on an "old" bike,why should they , they are there to sell you a new bike.
Your second question : Sounds to me that Joe Shmo took his bike to the dealership to have maintenance records. I have found that most bikes did run when they were parked but , there's no tellin what could have happened between then and now. Used anything is always risky.