Chess Etiquette

Hello, I am fairly new to the game of chess and chess.com. I am by no means a good player (as my 765 rank shows) but I have started to improve a little.  

On to the topic at hand. My beef is with players offering a draw when they are about to lose and when you don't accept the draw they sit there and let the clock run to zero. This has happened to me dozens of times. The game is late (I play 10 minute chess) with 4 or 5 minutes left and I am up 3-4 pieces and close to delivering the finishing blow when a draw is offered. Why should I accept the draw? Is there a "code" to follow? When I am down multiple pieces and obviously going to lose I play it out or resign. Or maybe I am doing something wrong? 

It's mildly annoying. I honestly don't think anything happens to the people doing this despite chess.com's warning "User X may have violated our fair use policy. It has been noted and their account may be restrictred." Or maybe you can do it 20 times before any real consequences because it happens far too often.

Some people hate to lose. Just ignore their draw offer if you think you have a better position. 

It's just an example of bad sportsmanship.

You are never obliged to accept a draw.  Generally, it is considered a bit rude for the person with the worse position to offer a draw to my understanding.  That said, playing it out or resigning is the respectful thing to do.  You just have to wait it out, maybe listen to a victory song as the timer ticks.