Personally i use big names as a good starting point.
Most people know what the major brands / labels / models sound like so you've probably got an idea in your head of what you're looking for.
Armed with this i'd then go into a shop and take a look, listen and play of what i think i may like the sound of.
If the shop is any good then they'll take what you've said you like and then hopefully suggest possible alternatives and "if you like that, then you might like this" just to broaden your horizons and maybe highlight something you'd never heard of or thought about buying.
If someone suggested something along the lines of what i was after and it suited my price, sound, quality and comfort then i'd have no hesitation in buying it even if it was made by Tesco Value!
My main two basses are a MusicMan Stingray and a jazz standard, this is because when i did play them they were exactly what i wanted.
I really like their sounds, feel and reputation - also the fact that the players i love also use them was a big reason to heading in that direction.
They also were in the ballpark of the budget i had and were perfect for what i wanted.
I try not to think that i only bought them because of their brandname, but i can't hide the fact that they are both pretty big names.