I was beginning to think that the hairy harmonica was something a bit naughty...hmmm.

steve wrote:I play the hairy harmonica pretty good.

But, can you hit the elusive G-note?

You may not have to be adept at performing an instrument, but you should have a basic understanding of the mechanics of any instruments you expect to encounter and basic music theory. Most of the work that I do is as an engineer with the producing left to either the band or the producer, but I still use that stuff every single day. When someone comes in to the studio with a poorly intonated guitar I can make it better. When the producer/band asks me to punch in an overdub on the second bar of the bridge, or after the modulation to F# or when when the bass player played a 7th that he shouldn't have it is my responsibility to know what the fuck he's talking about and to be able to do it. Not every band you'll ever work with is going to come into the studio fully-realized and needing you only to hit record. Sometimes they're going to lean on you for help with things that you should be able to help them with. I suppose it is your prerogative if you want to say "I'm just the engineer. You figure it out because it isn't my job" but I see my job as doing whatever my clients need me to do give them the results they're asking me for.