Op: If you want a better set of answers to your question Id think about posting on bimmerforums. The e39 section is generally more mature over there and they will give you more straight forward answers. There are only a handful of helpful suggestions on this thread...
Everyone: Lights can be replaced... easily. As for the paint job that's subjective. Different people have different tastes and for that reason there are numerous paint selections available from car manufacturers and even individual programs such as for BMW to appeals to those wanting to be extra different.. If you love it then you have your answer. I love how someone said this car has a crap paint job. There aren't enough detailed pictures to show such a crap paint job. A color not to your liking is not a crap paint job. A "crap paint job" is that which shows obvious signs of poor workman ship including but not limited to: poor prepping, tape lines, fish eyes, excessive orange peel ect.. So in order to make a statement such as the aforementioned credible, I'd suggest inspecting the car physically. If not keep it to yourself...
As for the wheels that's subjective as well. The same concepts as outlined above apply here so to each his own..
I'd do a PPI to silence all worries as well as check with BMW dealers for records of maintenance, check carfax and interrogate the owner on whom he bought the car from, conditions he kept the car in and do a physical check of the vehicle. If it turns out that there have been signs of abuse such as multiple accidents, non OEM parts galore which would compromise the reliability of the car such as Karlyn suspension bit ect and little to no maintenance, avoid the headache and find another car. If everything does check out try to reach a deal with the seller stating whatever value you believe the car is worth as per what was revealed during the PPI/carfax ect. On top off all of this read up on common issues on the M5board under the e39 section and perhaps start a thread asking for advice. When I wanted to buy an M a couple members were willing to meet with the seller and myself to discuss what to look for and for counsel. Like bimmerforum's e39 section, the m5board's e39 section is mature and they will lead you in the right direction.
Make sure to reach an agreed price before selling/trading in your car and do the PPI before all of this. If not it wont be worth your while.
So you guys can stop hyperventilating that this car isnt up to your standards.