Jordan, we are way off-topic here, but very briefly: a dead spot refers to a point on the neck where you just can't get much sound. You can play the note, but compared to the rest it is quite low in volume, dies out quickly, lacks character, and so forth.
To be fair, this is not unique to Fenders. It's a resonance problem having to do with length and mass of the neck, the frequency of the note, and all sorts of things. It just seems that Fender was unusually consistent about including one of these on their basses (I forget what note, but you can google it), and of course there are a lot of Fenders around, so it's sort of a standing joke.