Well,I'm no expert,but have tasted an assortment.
I also am priviledged to cook with some master judges.
We have a bunch of experienced judges and fine cooks here,that will have a variety of opinions.
As a judge,I look for one that tastes like BEEF.
Many judges seem to like a hint of sweet,with just enough salt,and a tiny bit of back heat.
Much sauce will kill you ,instantly.
Smoke is difficult to penetrate through large hunks of meat.
Because of its long cook times,brisket can oversmoke[ bitter,acrid,etc]
A nice aroma[ supposedly not judged]/taste of light smoke is nice.
The thought is that the seasoning will come from the heavy flavorful ,somewhat crusty bark exterior.
Texas contests do not allow sauce in the box,only cooked on the meat.
Texas and places in the heart of brisket county,would say "never sweet".
The Kansas area states, and some of the southeast, feel everyone likes a little sweet.
Now ,I didn't say that no one painted the back of the slices with brisket juice/sauce mixture.
A hint of spice,but not anything that stands out-or especially offends the taster.
The judge may only take one,or two bites,so cooks try to impact them then-without overwhelming.
Traditionalists would say all you need is salt,pepper,and a little garlic.
Some of us like a little heat with our food,but one judge that can't tolerate a hint of heat,and you may be done.
When you say taste,to a diner,they may consider how it eats,feels in the mouth,swallows,stimulates taste buds.
A judge will be giving a separate score for taste and then tenderness/texture.
It is that few degree range, that makes brisket.
It can be too tough to chew,or so tender it falls apart trying to remove it from the box.
It can be so tender and moist that it is mush in your mouth.
It can bite ok,but the longer you chew,the bigger and more dry it becomes.
It is not in the rules for KCBS,but some of the judging classes teach that" around " a 1/4" slice,held at each end,should pull "about" 1/4"-3/8" before breaking in two.
Texas may require it be the width of a number two pencil.
If it is cut thinner than that ,must be tough?
If it is cut thicker than that,must be falling apart?
Well,I better get-before someone accuses me of makin a Smokin' post.
Hope this helps a little.