No, they are not required. It's one thing when insurers make claims like this (and that's bad enough) but when I hear about salespeople going this route, I lose patience quickly. I wonder if this isn't laziness on the part of the realtor: they're going to take 6% of any transaction, regardless of how it's listed - so why complicate the ad copy and conversations with prospective buyers?

If I'm you, I insist on listing it as a 3BR - and know not only that there are there plenty of buyers who will not look at any listings for 2BRs, but also that there are plenty of housing market parasites eager realtors willing to help with your listing.