If someone has never or rarely played a double bass, this is a recipe for disaster. The intonation challenge is one part of it, but the other (and maybe more significant one) is purely physical. Ergonomics are different, the approach and techniques are different, and "fretting" notes require much more effort from your left hand and forearm. Cramping up and becoming useless after about 15-20 minutes of playing has a very high probability.
Egads, isn't that the truth? What you said can take years of dedicated practice to develop. I have a nephew that is a symphonic quality bassist. The hours he puts in are insane.
My experience owning and playing one is a little different. I could play some very basic stuff pretty much out of the box. After a day or so of practice I could be labeled a hack with bad intonation skills. A month later my intonation skills greatly improved, but I was still a hack… But I did play a few gigs and nobody complained, but I knew better, and gave it up. LOL!
Good post.

