Hey guys, I just started playing bass last summer; but I'm serious about anything I do. I have to admit that I started out with a video game, Rocksmith, but I didn't let my learning and experience end there. When I grabbed my first bass, I had on idea what I was looking for, but I did understand quality builds and quality components. Thanks to Craig's list and the generous Guitar Center return policy; I have been through about 25 bass guitars in the last several months. I play for an average of 3 hours each day and constantly learn and adjust to mimic the artists that have played before me.
There is no doubt that many used instruments have been improperly stored or mishandled. This may lead to warped necks or uneven fret alignment. Those two problems alone will make an instrument almost impossible to properly set up. However, my experience has been that with proper setup, tuning, intonation, and technique can make a low budget bass meet most needs.
One thing I truly believe is that a player should understand and properly learn how to set up an instrument. The only investment I have not yet made is for a quality set of nut files. Other than that; feeler gauges, micrometers, quality rulers, and depth gauges are standard equipment that are easily attainable and relatively affordable.
Another lesson I learned is that a brand name does not make or break the instrument. I had a "quality" MIM Fender P bass that I could never quite get right, and it was replaced with a dirt cheap 1994 Peavey Fury that is easy to adjust and tune. I once owned an Ibenez SR500 that played like a dream, but I just couldn't get the pickups and electronics to produce the tone I'm into. I have a Squier VM that sounds like a dream; but I prefer and play better on a Schecter Riot Session.
I suppose my point is that for a new player, it will be quite difficult to find an instrument that you will prefer after many experiences.
My best advise would be to learn what you expect in a quality bass, play several different instruments, keep a keen eye on the used market, and don't be afraid to trade or sell for another.
Eventually, you will find a preferred instrument. I have, but also I've found a couple that I intend to keep around because they are almost as good to me. The others just got passed on to hopeful other players that may prefer them more.