We get those offers all the time. We never go. On Bogleheads, they call the attendees with no interest in signing up, "plate-lickers". Mostly, they seem to sell annuities or insurance (whole life or long-term care). If you are interested in these items, you could do some research, including going to the dinner, and make an informed decisin.
We have a financial advisor that we're happy with. Every year, he treats his clients to an amazing dinner--last year, there was a lunch, as well. The dinner is in Dec., lunch was July. Anyway, no big pitch, no high pressure, just a nice meal with door prizes--we didn't win one last year, but I got the lovely floral centerpiece.