I heard that the room is as big a factor as anything else, but didn't believe it was that big a deal until I heard it myself, and my ears are not yet very distinguishing (i'm pretty new at this).
I tried it in different rooms and the sounds ranged from horrible to beautiful. At one point I had a stack of clothes next to the guitar and it's sounded peaky compared to when they were not there (same mic position, for a while I couldn't figure out why they sounded so different)
This is the approach I took and also what I would suggest:
Go outside and record the guitar. Make it sound closest to how you want it out here, and this way you will know what is an effect of the room and what is not. If it sounds really bad out here then something is wrong, maybe the guitar is bad or the strings are old...
Once you've found how it sounds best outside (even if you're not completely happy with this), record it using a similar miking strategy in every room you have available. You might even try staying outside and standing on a piece of plywood.
Even if you only have one room that you're able to do the final recording in, this process will give you an indication as to the character of the room and what it is doing to the sound.
If you want to deaded the room you can always get some pieces of drywall and staple a layer of fiberglass insulation and then carpet foam covering it. Pretty cheap and quite effective at deadening sound. Or just try old carpet or clothes or a corner full of packing peanuts (I haven't tried that one personally)
Um... I think I'm just rambling... late... uh... yeah.
