I have never understood why some people talk like it's a «rule» that a guitar tone either sounds good in a mix, or alone. When I noodle around on my Kemper I don't have one profile for that, and another one for playing to a backing track or recording or whatever. That may be because I really love my mids, scooping them makes me physically ill... What you're saying my apply to some people who love to scoop the mids for that "modern metal tone" though, but I don't think I'm the only one who happens to like the same kind of tones in a mix as well as alone.
To answer your question, I usually judge a profile based on what it sounds like by its own because it may give me that little something that I "need" to get the right vibe, to write whatever I aim to write at the time. I have plenty of profiles that sound great in a mix, and also by themselves but may not give me the exact vibe I'm looking for. So then I can use them for the vibe they have on its own, and for recording other stuff as well if the initial profile with the "right vibe" isn't the right one in the mix if you know what I'm saying. Sometimes it can even be a psychological thing, you crank up some profiles of a Marshall YJM100 and then you get the urge to play like Malmsteen (not that I can do that)Also, I almost practically live on the «Jailbreak Malcolm» profile from TopJimi's AC/DC pack and tend to use too little gain rather than too much
I agree I don't like too much scooped mids either. One reason I asked if you judge guitar sound from a well known mix is because so many guitar players ask how do I get this and that sound. I remember I once read an interview with Andy Sneap and so many guitar player have asked how do I get the clayman sound? You can't have it. They way it sounds is because how it was recorded and mixed, he said. Many love Dimebags scooped sound but it's fizzy as hell too. Never liked that sound. I think you have already answered your self. Like you said "Sometimes it can even be a psychological thing." Are you looking for something that doens't exist? Well too little gain is better than too much gain. Have you tried EQ the profiles you like? Post EQ? The latter can make a huge different from a little bit dull to a wow sound.