That I can believe! Poor ears for those nearby.
By good mechanical condition, I mean no rub, visible cone damage, torn surround, etc. I think it's pretty unlikely a bass VC will burn without leaving easily spotted signs of mechanical damage.
My point was not that you can't damage a bass driver VC with overpowering it, but that your much more likely to destroy the driver mechanically. I think the percent of burnt VC's in bass drivers is likely in the single digits. I'm a hack when it comes to repairing drivers and it's unlikely I would ever try to repair a pro/bass driver, much less charge money for doing so. Well, maybe if the owner had done something really bad to me in the past