I have reps on my car. They do get a bad press IMO but like all things, there are good and bad out there.
I would ask about warranty on the wheels first off. This will give you an idea of the confidence of the shop in the wheels, also ask about care / cleaning as some shops have different views. warranty wise, 12 months is std on usuall alloys but those with polished faces do have less in some cases, 6 months is the usuall. If they offer no warranty on the face of the wheel i would walk away, they would have had problems in the past!
Look at the laquer on the face of the wheel also. a good rep will have a think layre and look nice and even, this rep will probably be from Italy and the price will reflect this. If you can see lots of machine marks on the wheel (where the face was polished) that the layre of laquer is very thin and will be weaker to stone chips / bad weather etc.
I brought my reps because i knew where they came from and were confident they would last 12 months. If your not 100% then go for a wheel that doesnt have a polished face
Hope all this helps, if you have any questions drop me a PM........... this is what i do as a job so i can point you in a 101 directions