Don't get blinded by that lovely finish!
Bass guitars (like guitars) in many ways are like cars. Their appearance is a major factor in your buying decision. But also like cars, especially for the first-time buyer, there are far more important factors to know about in order to ensure you buy a bass guitar that is both properly playable and that stays in tune, enabling you to make progress with it. The unfortunate reality is that a lot of entry-level (and some not so entry-level!) basses are so poorly set up that they will make you feel that learning to play is just too difficult. The problem is, without experience, how do you know whether you are buying a playable instrument or just something that looks nice hanging up in the music shop? An experienced player can make a poor bass guitar seem reasonably playable, but the same bass could end up defeating the beginner's attempts to learn. So here are some basic pointers about what qualities a viable bass guitar should have.
Make sure the bass guitar has been properly "set-up"
For a bass to play at its best and to be as easy as possible to play it needs to be properly "set-up". This can be split into two key areas, "intonation" and "action". Correct intonation means the bass plays in tune both with itself and with other tuned instruments all the way up the neck, i.e. although the open strings might be properely tuned, you may find that when you play higher up the neck it is no longer in tune either with itself or other instruments. Good action means that the strings are set close enough above the frets to make them easy to hold down, but without causing unwanted buzzing of the strings against the frets under the vibrating portion of the strings. Some budget instruments have a nice finish but in reality are so poorly put together that they can never be properly set-up, check before buying.
To check intonation, play an open string and listen to the note carefully, then play the same string again, fretted at the 12th fret (this usually has a double dot marker on the fingerboard just before it). This note should be exactly the same but an octave higher than the open string note. You can also then play the "harmonic" note at the 12th fret (to do this place your finger lightly on the string directly above the 12th fret without pushing it down to the fret, play the string and it should ring), it should have the same pitch as the fretted note at the 12th fret. If you can hear a difference in pitch then the intonation is out and needs correcting.
The action is affected by three key factors: neck-curvature, bridge/string saddle-height and nut-height.
Firstly, a bass guitar's neck should have a very slight curvature in it in such a way that when you hold the low "E" string down both at the first fret (F) and at the highest fret on the same string with your other hand, the middle of that stretch of string should be about half a millimetre above the frets. This curvature can be adjusted by tightening or loosening the guitar's "truss rod" - best left to a guitar tech as over tightening can result in a broken truss rod and/or a ruined neck. On budget basses you may find that half a millimetre causes too much fret buzz and may it need to be a little more, a top quality bass could be less as the alignment of the frets will have greater precision.
String saddle-height can offset this buzzing to a certain extent. Adjusting this will provide the best string to fret angle, with the same aim of to keeping the string-height as low as possible whilst being just high enough to eliminate fret buzz. To get the best possible action from a bass you need to have the optimum combination of neck curvature and bridge/saddle height.
Nut-height is the third factor affecting the action. The nut is the piece of (usually) plastic or brass that holds the strings in place at the head end of the neck. If the string channels are the right depth the strings should be less than half a millimetre above the first fret, on a quality instrument they could be almost touching the first fret. It should be quite easy to hold a string down on the first fret. If you have to push the strings down a long way here then the string height all the way along the neck will be higher than it needs to be, making the bass more difficult to play and making learning seem that bit more challenging.