I'm going to suggest trying out a bass before you buy it next time...

What attracted you to a Stingray in the first place if you didn't like the tone? I'm assuming you heard one and liked it, so assuming you like the "Stingray tone", and this one sounds like hell, maybe there's something wrong with it. Take it back where you got it, or go to GC and try another one. See if they sound the same.
Try playing with a light touch, that will lessen the treble content greatly. There's truth in the train of thought that the the sound is in the fingers.
Stingray's have the potential for a lot of treble, but also a very cool gravelly ultra "jazz bass on bridge pickup" on steroids sound, which is very deep, but tight rather than muddy.
Its either the bass or the player.
Randy