History: The term "salesman" came about quite early in time, and was a role most frequently filled by the male half of our species. Of course, things started to change in the late 1800s and we got into the full swing of being politically correct in the late 1900s.
Salesmen and saleswomen started becoming "salesperson," which is an uncomfortable word to pronounce, so other words were created in its place... "Sales clerk," "sales attendant," "sales associate," and a myriad of other sales-beginning things. Even the word "clerk" has started gaining in popularity recently, reflecting English's tendancy to use shorter words when available.
So what is it? What does being a salesperson entail? At the most basic level, a salesperson is responsible for the sales of a particular product or service. Any further observations beyond that are usually unfounded - such as saying "all salespeople are nitwits" (Dekaritae).
Some salespeople do nothing to actually encourage selling a product - for example, the person at the till of a grocery store is, by definition, a salesperson. For that matter, a buddy of yours that says you should try a certain beer is also a salesperson. Most Wal-Mart employees are salespeople, Best Buy is filled with them, and Future Shop (in Canada) is known for their lackluster sales team. Real estate and used car salespeople are a completely different breed, and halfway in between you get the furniture sales team.
Big Box Stores: The quality of a salesperson largely depends on their wage. Best Buy and Future Shop are minimum-wage employers, paying their salespeople as little as possible (slightly higher than minimum wage actually, to curtail an out-of-control turnover). As a result, most of the employees are young or in an entry-level position, and don't even want to be there. These salespeople don't care about Joe Consumer, and they don't care about saving you money or making sure you get what you want. All they are concerned about is making their monthly quota. A quota is always set in terms of amount sold - so if you sell 50 not-so-good televisions, you'd be doing better than a fellow salesperson who sells 10 excellent televisions. The difference is that the crappy TVs are easier to sell than the expensive ones. Net result? These "not-so-good" salespeople pressure you to buy inferior products, just to make their quotas go up.
Specialty Stores: I was personally a salesperson at a furniture store, The Brick. It was a suit-and-tie affair, and obtaining the trust and friendship of a recurring customer was key. It was agonizing to see someone pull up in a Lincoln Aviator with $20,000 rims, and have them say "oh, sorry, I only deal with so-and-so. I'll be back tomorrow."
This particular store has a very simple employee payment scheme. Each product has a certain percentage affixed to it (not physically, of course, but in the computers). This is the amount of money that you get for selling that product. Obviously, the more expensive the product, the higher the percentage. For example, a small coffee table costs about $50 and pays 3%. That's a whole $1.50 commission - woowee! But it sure makes your day when you sell a 15% commission mattress, that retails for $2500. That's $375 commission, which pretty much just paid for 3 days of work... for a 30 minute sales pitch.
"So," you think to yourself, "the salespeople will just pressure me to buy the most expensive stuff." Well that's the catch. If I were to press someone too hard into buying a $10,000 TV, they'll just laugh at me and walk away. It's much more profitable for me in the long run to score that Lincoln Aviator as a customer. Listen to what he wants, pick out the best thing for him, and make $50 today. Make $20 tomorrow. And maybe, when he buys his new house, he'll buy a 7-piece appliance package, a new Plasma TV, and a giant king size bedroom suite to match his new leather livingroom. A score like that could easily make you a few thousand dollars for a mere two or three hour's work.
So you see, it is much more rewarding to not pressure people into buying what they want. And you'd better beleive that the Mr. Lincoln Aviator knows all about his leather - and if I can't tell him why one leather is better than the other, he won't be able to trust me. I won't be able to make that sale. And he'll be looking for a more knowledgeable salesperson. Being educated in the product you are selling makes you more money.
Automotive: Now for automotive salespeople. Take the above example but remove the need for getting a recurring customer (after all, how many cars do you buy per year?). Suddenly, you are left with a highly-paid, well-knowledged person who doesn't really care what you think of him or how he treats you. You came to Ford (or Chevy, or whatever), which means you want a Ford vehicle. You must suffer through the salespeople at that dealership. This is where trouble starts happening. Mix greed with high pressure sales (and by that, I mean the manager is highly pressuring his salespeople) and a disrespect for customer service, and you've got one heck of a headache on your hands.
Real Estate: Real estate is even worse - more money is flying around, and again - you can't go through another agent to buy that dream house of yours. You are stuck with that agent, no matter how much you despise him.
Conclusion: If you dislike your salesperson, get a new one. Just say flat out to his or her face that you don't like their lack of knowledge/attitude/high pressure, and you'd like to deal with someone else. This will give the employee a hint and maybe save the next customer (which could be you!) from suffering the same dummy. There are nice, helpful salespeople out there - you just have to find them - and remain loyal to them.