Very interesting. This has been on my mind for a bit now as a similar-ish scenario was brought to my attention about 2 months ago with an acquaintance of mine who's been on cycle for the 2 years or so (moderate/low by bodybuilder standards at 500 mg/week but still a superphysio dose). He's had the same issues with having to steadily increase the arimidex dose to achieve "good" horny feelings.
Granted he hasn't done the blood work, but when I asked him about his adex doses he said he understood the need but he was poor. He'd started at about 0.5mg ED feeling fine, good mood, good morning wood, very stable and very...ah...lusty :). Over time he got to the point where .5 mg/Day wasn't enough to keep morning wood and eventually he got itchy nipples, and modulated the dose higher. He is now to the point that he is at ~ 1.4mg/Day arimidex for morning wood and good libido to occur on same dose of Test.
For what it's worth, I know he uses the liquid variety, mixed himself from base powder at 1 mg/mL in plain but drinking safe ethanol.
I know it's not your forte KSman, but when I stumbled across this thread I had to ask if you had any clue as to what I could tell him to do. I'm not a big advisor or anything, I just have been puzzling over it because I like puzzles :). That and he's a nice dude I'd like to steer in a good direction if I stumble across anything.
I was wondering if it might be just the shelf life of the arimidex mixed with strong alcohol, possibly breaking down (I have no knowledge of decay rates of adex in alcohol, I just know it is freely soluble).
Aside from that possible issue--pretend it's perfectly good adex--do you have any further idea of what might be going on?
Sorry for the hijack OP! ---didn't mean to do that, stumbled across this thread by accident...but I figured it was pretty well related to your stated problem and I didn't want to start a new thread for the same problem :).