I have had my car dyno'ed 4 times now - twice at Awesome, twice at PDT(Sedox)
Each time I always have that excitement of potentially knowing how the mods i have done might affect torque/hp but that is always offset by the dislike of seeing the nuts revved off your beloved motor and it not actually going anywhere. In fact I have not yet had a run which did not highlight problems.
Is there any evidence to show dyno runs can actually damage your car?
My distrust of them is in part is fuelled by fact that after my last one my car was fooked and i had to have new gearbox, slave, master and DMF!
Now, there was no evidence that the dyno was in anyway responsible for this; how could it be? Merely, that the dyno run highlighted the problem and exacerbated it accelerating its demise.
On the other hand should you view a dyno run as a health check, as it highlights any problems before they get out of hand eg boost leaks, issues with EGTs, timing etc?