Depends what you are looking for in the car. If you don't care about resale value and want something that is inexpensive, a car with imperfect title may make sense. It goes without saying that such a car would have to be inspected very carefully by a competent body shop and BMW mechanic. As long as you go in with your eyes open to the potential problems, including reduced crashworthiness if it was in an accident, you should be okay.
If it was me, I would not buy a salvage M3 unless it was to build a race car.