I entirely agree with the red hair bit. I am a red head with fair skin and the heat + humidity absolutely kills me. When I was a child I lived in Singapore (very high humidity) and was apparently very miserable but when we lived in Egypt I was fine as it is a dry heat. It could be nature as we tend to burn very easily.
I think it must be the humidity, or maybe the combination of both, that gets to Andy, because he's usually OK with the heat in Oz, which is a dry heat.
I do remember Andy having a mild heat injury at Cincy one year and then could not cope with the heat at USO either. It is not always because you not drink enough.
Yes, that was in the Cincy QF against Fish, but Andy had been playing earlier matches in the heat (in Toronto as well, as I recall) and a request for an evening match was refused because Fish was playing doubles later. Unfortunately I don't think Andy took the break he should have done afterwards and so was affected again at the USO. Heat exhaustion can be serious and I think Andy under-estimated that fact.
I've now read the BBC report and thought it was very grudging. Yes at one level Andy was unconvincing in that it was more of a struggle than it needed to be. But they give him insufficient credit for hanging on in there and finding inspiration at key moments in the match against a for the large part inspired opponent.
The BBC report really made me angry. What short memories their reporters must have! They seem to have completely forgotten about Andy's gold medal, and the silver too (oh they were all over him like a rash then) and the fact that in playing and winning for his country he was not only tiring himself out by foregoing a decent break but also that he missed his usual acclimatisation period in Miami.