They seem to comment on everything else but this o_O

It's funny because Smithing is probably the only skill anyone actually publicly displays using in town on a regular basis as well

Actually they kinda do, when you wear dragon armor they'll comment on that but further then that no

I had one guard say something about my "sliver of midnight" referring to my enchanted ebony sword once. Other than the dragon armor comment I've not heard anything.
I'd like to give that one guard a better sword though. Atleast one that can cut butter.

I like enchanting a sword and naming it "Butter Knife" and reverse pickpocketing it onto a guard that makes that comment.

they'll comment on some armor and weapons but not directly at your smithing skill.
Yet they'll call you a sneak thief if you've never stole a thing.

"Look at the smithing on you".

they asked me to smith them better weapons i smith a dragon sword for nothing

LMAO! I'm definately going to do this one! That is so funny. I may even do it that one that tells me he's going to cut my hand off.

They'll usually comment on what weapon you use (Ebony, Elven, Glass, etc) and how it was forged, but that's about as close as you'll get. Last night I just went through all of the guard's comments on UESP and I believe there was nothing on smithing. Could have missed it though, as there are SO many comments that guard's make.

Because 'You look like you could hammer something' is more of a come-on than a comment.