You should definitely contact Axiom about the glue. That is not normal, not even for outlet speakers. You shouldn't see glue, anywhere.
The room itself and the placement of the speakers in the room will affect the 'robustness' of the sound quality.
My den is somewhere around 3200cu ft, and has bare hardwood floors, hardwood paneling on the walls, and many large windows. It is an acoustically bright room. If I run my m22's on their own in there, they sound pretty weak. I actually think 'thin' is an apt description - because that's how I would describe it as well. They have bass, but it's not enough to really hold down the bass end, at least compared to the mids and highs. A good sub, of course, completely fixes that problem.
In my bedroom, where the m22's live now, the room is only about 2000 cu ft. Big bed, heavy curtains, rugs, etc make it an acoustically warmer room. The M22's sound much better in there. Much more balanced and pleasing to listen to. And no sub, just pure m22's. Plenty of bass. Even a bit of 'thump' to them, which surprises me. They sound great. I'm sure the size of the room has something to do with it too, but they just have a lot more presence in that room. I'd almost go so far to say that they sound like different speakers in that room, compared to the den.
That, or it's a difference in the amplification between the den and the bedroom - which I know would start up a firestorm.
Burn-in is a hotly debated topic. Many (including Axiom themselves) say that it does not exist. Or that if it does, it's accomplished within milliseconds of applying power to the speaker. Others will say that speakers need X hours to reach their potential. I've read many a 'professional' review where the reviewer stated that he left the speakers playing for X days and they sounded better after that. So.....
We've had many people show up here with new Axioms claiming they're bright and thin, and after a few posts they'll say that they're sounding better. You would be another one.
So
something is going on. My feeling is that just like how people dislike certain foods or situations at first but later grow to enjoy it, speakers are the same way. Adaptation is one thing that we humans do pretty well. Or maybe it is actually burn in. Who knows.
Good luck! And seriously, if you're not happy with them, return 'em. That's what the 30-day return policy is for.
