A few years ago now, my mate took his nissan suv to get its regular service (supposedly capped price)
he thought he would give it a thorough clean, including a full engine bay degrease and clean before he took it in (same reason you did yours @El Andrew )
when he went to pick it up there was an extra charge on his bill for an engine bay detail
he's not one to hold back, so you can imagine the size of the new butt-hole he ripped in the service manager