Good point.
When only the descriptor "porsche" is used in a Craigslist headline, it turns out to be 944. 924, 931 or 914; never a 911, at least in Southern California.
The ads saying "1957 Porsche" almost always turn out to be a fiberglass Speedster replica with a VW VIN.
Oh, with the occasional surprise:
'57 Porsche
And the occasional Varrera:
http://losangeles.craigslist.org/sgv/cto/1642437225.html