I know a good visual clue to bad mounts can be seen on non m engine mounts as they will create a hole in the hood insulation right above the power-steering reservoir cap. I changed mine out in the blown 330ci at 120k
On my current m3, @ 40k miles, last time I chcked it looked good will be looking for one at around 60k with new spark, and general maintenance
"One thing we all adore. Something worth dying for..
Its been nothing but pain, stuck in this game. Searching for fortune and fame