Why does a dent to a tweeter not affect sound quality?

OP said dented TWEETER.

not a dust cap, the material of the tweeter's driving face, designed specifically, by computers, by sound analysis in industry designed chambers, to  push air at accurate infinitesimal frequencies, the surface creating the accurate specifically designed polar distribution pattern.

Ye that buy fuses, horribly expensive tweaks, and have the nerve to say, my ears aren/t aged like science says, I can hear highs, I can tell the difference between this and that, 

OMG, stay away from dented tweeters!

"... jumped right through my right channel Maggie on LSD."

!?

...I can't even imagine what the rest of the evening went like....

Can you remember what was playing when she tried to 'meld' with it?
If Anything from the G.Dead....I can understand (kinda) That..;)

(....yet another case file from "White Punks on Dope".....) *L*

It might affect dispersion at very high frequencies and also cause VC alignment problems as previously mentioned 

Here is a fix. place a dab of thick cyanoacrylate glue on the end of length of sowing thread. Swing the thread into the dome so the dab just contacts the dome at the center of the dent and sticks. Carefully drape the thread over the top of the loudspeaker without pulling it off the dome and leave it overnight. The next day gently pull on the thread until the dome pops out into (hopefully) it's original shape. Then carefully snip the thread and as much of the glue as you can take off the tweeter with fine angle cutters. Any glue remaining on the dome can be removed with acetone. This is how auto body guys pull dents. They weld rods to the sheet metal, pull the dent then grind the rods off. I would not try Bondo on the tweeter;-)

I would never buy a pair of speakers that the tweeters were pushed in/dented on.

Even if they were "sucked out" or pulled out whatever. If they're wrinkled, pitted, whatever.....the answer is simple.

"No, thanks."