I did a session back in I think 74' - and as often happens an assistant engineer comes out to mic the kit. He informs me that he wants to put some muffling on the toms (they had not even brought the drums up on the board

). By the way - I was using black dots - with all the bottom heads removed

So, while I was not overjoyed - I found I got more work being easy to work with - so I told him to do what he had to do. I left to stack my cases in the outer haul and quickly smoke a joint (hey....it was the 70's)
I come back and this guy had covered more than half of each drum head (including the snare) with big pieces of yellow foam (using duck tape

). Fortunately, the doobie helped me to just laugh it off. I stood by the drums until the engineer motioned to me to put my phones on - and when he told me to hit the drums - leaned into the snare mic and said...."I can't". He asked in a voice filled with attitude - why, and I said "I can't find my drum heads man - they're like, buried in yellow foam" (that's how I talked in the 70's

).
The engineer come out getting ready to be a dick (many engineers think their shit don't stink). He stands behind the drums, looks at me....and we both laughed. He informed the assistant (who it turns out was a guitar player -which really explained everything

) that he was an idiot. We got a roll of toilet paper and some masking tape (which I always have in my case) and I treated my own drums.
Next time I was in that studio (a couple months later) the assistant was no longer an employee.