To me "loaded" is an old school car selling term that use to mean things like power windows, locks, A/C, cruise and maybe power seats or sun roof. However, things have changed and depending on the car most of these items are standard features. The Japanese and to a certain extent some of the European brands have changed thins up by offering cars with trim level where (i.e. Accord EX vs. Accord LX) the trim determines what the car comes with and then there are limited options to choose from. This day and age I consider it to mean one of a couple of things: the seller doesn't know what he/she is selling, or the seller is an old school type of car salesperson; or the seller is marketing the car to people who don't what they are looking for or buying.
As a side story to this....as a Porsche fanatic I get a laugh out of seeing various Porsches advertised in Autotrader as loaded when in reality they have virtually no options except for the standard equipment (which includes power windows, locks, etc.).