It can be difficult to assess the qualifications of a prospective instructor as a DB novice. A good starting point might be to watch the teacher play, observe their technique, listen to their intonation, and watch them sight-read music to see if their technique provides a strong foundation for sight-reading.
Do they have tone you want to emulate? Is their command of the instrument readily apparent? Can they explain what they're doing in musical terms that a new student can comprehend, i.e., is their teaching style congruent with your learning style?
I'd like to see a compilation of video clips on TB, vetted for credibility by our TB instructional gurus, in which there is consensus that the featured bassists are exhibiting technique worth emulating.
Viewing several such videos might not prepare a student to play the bass, but students might be in a better position to select a qualified instructor once they know what great technique looks like; why hire a teacher whose technique is questionable?
I wouldn't hesitate to recommend Ray Brown as an examplar of great jazz technique because he gets a great sound, his technique is very consistent, it's easy to see exactly what he's doing with his left hand, and he ably demonstrates how he exploits gravity to achieve power and articulation while playing. His technique yields great intonation and dynamics, and supports sight-reading. I also admire the self-discipline it takes to learn the bass part and the melody for every song, in every key. I wish his bass method book included a video showing how he plays the exercises, but it's a good book for beginning bassists nonetheless.
Who do the rest of you recommend?