What actually makes a good recording room ? Or to put it another way, what makes a room bad for recording ?
In a house, is it a given that a room, unless "treated" will have a detrimental effect on whatever is recorded in it ? What factors determine it's goodness or badness ?
Good question. I think that Greg probably nailed it with the first reply in the thread. It really would depend a lot on what you're trying to achieve.
I personally don't think the room matters that much for tracking if you're close miking stuff. Note that I said "that much" and not "at all". It matters a ton for things that use the room for sound - like piano or drums or vocals. I can position my drums in different spots of one room and get vastly different sounds. The room matters a bunch when mixing. A good or bad sounding room is totally subjective and depends on whatever you're trying to achieve. A stairwell will probably suck for most things, but might be just right for a certain sound you're trying to get.
I think that it's worth making a distinction between home and pro situations. Giving that this is HomeRecording.com and not LetsSpendaMillionBucksOnaProRoom.com then the priorities can be rather different. For me, audio perfection is not irrelevant but it's still pretty low on the list, for practical reasons. Mostly, I'll use work-arounds rather than try for a perfect room. So my priority list looks something like this:
- 1. Roomy and comfortable. I don't want to have to pack and unpack the gear every time I do anything. I want to leave stuff plugged in and also have room to add and subtract things when needed.
2. Under my control. I want the flexibility to decide to runs wires around, drill holes in the walls, move furniture, or stick experimental baffling up if I feel like it.
Home hobbyist situations probably range all the way from trying to record a worse than average band in a tin garage on a single hand held recording device through to some quite sophisticated track by track stuff. So I'd guess that for us, there is no ideal room because we don't have a standard way of working or a consistently fixed set of requirements. The best we can usually hope for is somewhere that is potentially a bit adaptable, depending on what we want to do this month.
So my room has carpet on the floor, low walls, a tent like sloping roof, and not a lot of bare exposed walls. When I've run test audio files it soaks up some frequencies and boosts others, as you'd expect. But it's not much worse than my mate's studio, and he does commercial work in his, and has some treatments on the walls (admittedly not very good ones!). He's used to the characteristics of his room, I'm starting to come to grips with mine.
Like Greg said, if you're recording mostly straight in, and you can shift things around a bit and mic fairly closely when needed, then I don't think there's much trouble getting 'within reasonable tolerance'. I don't require perfection, just a reasonable good standard and an appreciation of where the weak points are. Importantly, I don't want to record entire bands at the same time, in performance mode, using longer range mics. So the room doesn't need to be all that good, it just has to be not totally horrific - or leak!
But, of course, if at some time down the track I get bitten by the 'room treatment bug' I may completely disown the above opinion and spend many bags of not particularly essential dollars on a holy grail that I probably don't really need.

Hobbies are like that... a great opportunity to find excuses to spend more money and get mildly obsessed by things...
Chris