Not sure why but I feel the same about it as you.
When I see the type of wording used in this ad, I'm always suspicious, although I suppose it could be true. "don't know much about it, I just play my precision"
Generally but I guess not always, people who have four basses tend to know what they are about and how they function.
It might be genuine but if you are worried, then back away. I do, safe in the knowledge that there will be another one along at some point.