One_Dude has it covered.
Beat me to it. The 'sight up and down the neck' test is the first thing I do, even on new basses in the store. Will asymmetry in this test always indicate a bad bass? The serious gear guys here can answer that but if there's a significant difference, it's a red flag to me. Also agree with the signs of neglect. It tells you a bit about the seller and all information is good in a transaction like this.Signs of abuse or neglect could be rust or corrosion around any jacks, screws, or hardware, or an overall dirty appearance with numerous finish dings or dents. Also. check the string wrapping at the tuning pegs to see if it looks like the person installing the strings was careful in their installation, or just slapped them on. To check for a warped neck I sight down the neck from each end, both the head end and the body end. If the neck appears to have noticeable high and low spots along its length (kind of looks wave-like) it could mean the truss rod has been over tightened in an attempt to straighten a warped neck. You can also see a twisted neck using the same method. Both of those conditions would stop me from buying unless the price was low enough to warrant replacing the neck.
Yep, this too.I were the seller I would not appreciate a potential buyer who may or may not be qualified making adjustments on MY bass.
.