As far as I know there is no law (other than truth in advertising, and the lemon law - correct me if I'm wrong) that holds a dealer responsible for a product that isn't what it is actually advertised as. There are so many examples of products being advertised as something they're not (think the Showtime Rotisserie BBQ), this forum does not have enough space to elaborate on them.
However ..
I've bought two basses from this dealer (if it's the one we're all alluding to ...). They were exactly as advertised, and I made sure to ask questions. Ultimately, it is on the buyer to ask. If they don't, and get something other than advertised, they shouldn't be surprised. They should, however, be a bit angry at themselves for not inquiring prior to the sale. The dealer is there to make a living, not be your buddy. Sad, but true. If he can get you to buy something and make an increased profit, it's good from his perspective. Does this make it ethical? Probably not. Does it happen? Yep, every day.
Of course, if a dealer keeps doing this, eventually word will get out and people will stop patronizing his business.
Think about it. We buy new and used cars. Would one buy a new car, for example, without asking about certain options, payment plans, warranties, etc.? Nope. A house? Hell no. Same goes for high-end basses. One should ask what it is and isn't. If one doesn't, then caveat emptor ... buyer beware or be aware, as has been previously mentioned.
I can only speak from my experience with this particular dealer. He's done right by me in two transactions in excess of $5K (one Alembic, one Pedulla). If it was on his site, and the buyer didn't ask questions, then it's on the buyer IMHO.
My two cents,
Alan
P.S. You can spec out an Alembic in so many ways ... I get confused just thinking about what the serial number should read .... However, in the end, it's still an Alembic. To me, that puts it head and shoulders above anything else out there, serial number/model be damned.