here's some history;
the Huffman Manufacturing Corporation started making bikes in 1934. they were well built, solid bikes back then. they also made bikes for numerous other companies, like Dayton, and also badged their bikes for various department stores to sell.
in 1953 they changed to Huffy, and during the following years concentrated on building department store bikes, and the quality went down from the '60's on.
in 1999 they closed all their american plants and moved production to china.
since the 70's BMX and ten speed boom, Huffy has always been the butt of jokes. there used to be stickers like "If Huffy made airplanes, would you fly in one?" they produced cheap, disposable bikes, while not exactly junk, they were designed for the casual rider, and even their BMX bikes came with "warning" stickers that they were not designed for "stunt riding, racing, or jumping."
to answer your question, your american made good vibrations bike is of better quality than todays china-made huffy, and the salesman was either BS'ing you, or is a total idiot.
but...
your american- made huffy is now 30 years old and wasn't built with durability in mind, so depending on condition, it could be better, could be worse, or could be the same as a new one.
buying a new huffy is definitely NOT an upgrade. it's just buying another cheap bike. this forum's filled with broken huffys (to be fair, there's many successful huffy builds, also.)
for your first bike, the good vibrations cruiser is a good choice. learn all the mistakes on it, and build a better one next time...