I've only just latched onto this thread

and am finding it really useful.
I personally 'find' the key to a song by finding out what the melody notes are (by experimenting with playing along while listening). Then I know what key it's in because I can see if there are sharps and flats and which they are etc. This also tells me if and when a capo is being used because if it sounds like it's in Bb (or some other unfriendly key) you can be sure they are using a capo.
Mostly the songs are in C or G and +/- a capo, and then usually follow the I IV V - or a I IV V7 with the occasional vi or similar. However, I reallise that I am relying on reasoning and not my ears. Is this stopping me from developing my 'ear' do you think?
I'm hoping that with practice my ears will take over and I will get those 'special powers' that I long for

One good thing about music is that when it hits you, you feel no pain - Bob Marley