I am usually the last person to jump to the defense of a company, even in the face of faulty hardware... but in this case, I feel I need to defend Samsung just a little. Like you, I have had tons of Samsung harddrives, even sent two (or was it three?) in for RMA after they got bad sectors after a few years (there isn't much anyone can do about that!) and have had all around good customer service. Even for that typical customer who had his drive go AWOL two months past the warranty.
The problem with something like an 'annoying noise' that is at the edge of ones hearing is that it is nigh impossile to diagnose. If you send it back, you just have to hope the technician(s) can hear it, or you'll get it returned with an 'it works as advertized'. Similarly, some harddrives are created for performance, and as such are put to less demanding silencing tests. Companies simply have to accept the fact not all products coming from the assembly line are perfect, no matter how much QA they throw at it. Thus, when you have such a problem, you should be able to return it to the shop within a week or so of your purchase date and get the frustration over with, or get another drive - possible from another manufacturer. (I assume that the USA has some sort of laws about returning goods within some period since purchase.)
The last thing I want to touch upon is that I consider it a bit short-sighted to blame a whole company for one defective product. You say tons of people have the problems you experience, which is allright. The problem is that if you'd look, I bet you could find similar complaints about every hard drive manufacturer. Google makes it pretty easy to find the dissatisfied <0.01% of customers that has your disapproval, after all. (Sadly, I speak from first-hand experience there; I was in a rather similar situation to you a year ago with another product.) Hard drives spin at 5400/7200/10000RPM: that is bound to generate noise. With everything getting smaller-faster-bigger-better, hardware simply becomes more sensitive. Maybe your drive was jostled a bit in its shipping; who knows!
I don't discount your experience. But especially given your good history with them, I'd either have given them another try or simply returned it. I absolutely hate you
is a strong statement for something that the customer service concept was invented for.
(Btw, I know you are a usually totally relaxed person, so I'll blame the noise for driving you batty and upset.