I've been around cars for more than 30 years now (just had my 30 year anniversary of passing my test!) worked in the motor trade for VW/Audi and at body shops in the US and rebuilt a number of vehicles of my own and worked on countless others. Of course one takes a careful look at the work one has paid good money for but in the previous case, it was a blindingly sunny day, the car was cleaned and the new paint appeared to blend well with the old. The job cost £200 cash and to be fair, it wasn't bad even when I contemplated the mismatch later under less sunny conditions. It does appear though that the clear coat has yellowed somewhat; it looks worse under certain light conditions. Now however, an insurance company is paying for this repair, the work has to be up to scratch(!), they will replace both bumper parts and paint to my spec. including the lower panel to black. A fine tooth comb will not be fine enough and it'll not be accepted unless I'm totally happy. Thanks for your interest.