Why do you say you're a south Boston hotel when you have an 02125 zip code dorchester address & tel. exchange?

Dorchester is a neighborhood in Boston, although not Boston proper, it is passable marketing...

I know a few businesses that do that. I think its because Boston is more well none and sounds more sophisticated

Since the convention center is in South Boston, marketing people expect that convention travelers will tend to search for hotels in South Boston. In this case, a hotel in Dorchester is presenting itself as a "South Boston" hotel to tap into that traffic.

It's not unusual for hotels to do this: around Route 128, there are hotels with names like the "Woburn-Boston ... Hotel", the "Newton-Boston... Hotel", etc;, and they're 10 miles away from downtown!