Just my 2 cents:
1- After I poke holes in the eggplants, I have a tin can cover (or aluminum foil) that I put directly on top of the burners on the stove top with the eggplants sitting on it. This is the closest way to get the "burnt taste" that is common to good baba ghannouj.
2- no garlic
3- I also add half a cup or so of thick yogurt (yogurt that I drain in a colander by placing store yogurt with a paper towel underneath and let it sit for an hour or so). That just gives a really nice color and adds taste.
4- of course lemon, salt and pepper. And, the key is the tahini. Bad tahini will ruin the whole thing.
I put the eggplants (that usually get really burnt), in the blender after cleaning them.
and then mix by hand with a fork the rest of the ingredients.
Elie