- Don't buy sight unseen. Avoid mail-order basses that promise the world with their marketing. Even the "famous" ones. Yes, that means you

.
- Avoid "all-or-nothing" statements
I agree with Eric that it is better to see, touch, hear, feel, and play any bass you are considering buying. I think of "mail-order" basses as the ones sold by guitar shops and on-line music warehouses. If those are the basses to which Eric is referring, then I'd advise as well that you avoid them. They are almost always poor values for the money.
There are also basses that are shipped by real bass shops and set up by real luthiers (e.g., New Standard, Shen, Upton, Wan Bernadel). Again, while it is better to experience any of these in person first, I would not say that any of these should be necessarily avoided especially if you can play them first! So, no, don't specifically avoid a brand simply because it is often shipped. I suspect what Eric meant is that one should avoid mail-ordering these basses sight unseen and sound unheard rather than that one should avoid the basses,
per se.
Now, about this sight unseen and sound unheard issue. IMO, it becomes less important to try first as the price-point decreases. Now, before everybody pounces, here's what I mean. I don't know anyone would or should drop $20k or more on a bass without trying a bunch first. That just seems patently absurd. At the entry level (e.g., $1500-$2000), however, which seems to be the level of interest for
dsperry, there are, IMO, precious few instruments that are worthy. Here, I could easily see buying a bass sight unseen and sound unheard via the recommendation of a teacher or other trusted veterans. Still, it would be
better to experience the bass first. Sometimes, though, that's not all that practical.