Florida started registering dirt bikes and quads in 2001 I believe. I have a 1999 WR400F that I bought new, it came with a BOS only from the dealer. In 2001 I bought a Honda Rancher, and it came with an MSO that the dealer had to mail to the DMV. In return I got a title in the mail that said "for off highway use only."
So it depends what state you are in and the year of the bike. I understand there is a mechanism to obtain a title for my Yamaha, but I only ride it on private land and have the BOS for proof of ownership. If I was going to ride it at an OHV area, I would need to get an off-road title for it.
But, I recently bought an XR650R that had been tagged and titled in TN since new (2007). Because it was already tagged in another state, I was able to get a street-legal title and tag in FL. If it hadn't been tagged, the best I coulda done was register it in FL as an "off-highway vehicle" and the title would have said so.