My experience with TSA is limited to only two airports - BWI and MCO - since I only fly when I go to WDW, but I've never encountered any of the crap that I read about on the net.
TSA agents don't always smile and act like they're happy to see me, but some do, and I've had some nice conversations with the people at the beginning of the security line at BWI (ONLY when there is no line, early in the morning - I refuse to back up a line of any kind with idle chit-chat).
I've never had any difficulty with the agents at the metal detectors or x-ray belts.
I once forgot to take my cell phone off my belt and set off the metal detector, so I got pulled aside for wanding, and the agent seemed almost angry about having to do it, but he wasn't rude, did his job, and everybody parted happy.
Before I went digital, I traveled with a bag of film, which I asked to be hand-inspected on every flight. I never had an agent bat an eyelash at the request, let alone refuse to do it or give me any grief over it. An agent once asked me why I asked for hand inspection to prevent x-ray exposure, yet handed my bag to him through the metal detector; I cheerfully explained to him that the metal detector has no effect whatsoever on photographic film, but x-rays do. He was a pleasant fellow who did his job quickly and was appreciative that I took the 30 seconds or so to explain it to him.
The "traveling public", on the other hand, gives me more grief than the TSA. I've been jostled and bumped, had my rolling carry-on tripped over (while it's sitting still next to me), I've been stuck behind people who don't understand the regs and won't make any effort to obey them, and of course, there are the folks who complain incessantly about the length of the security lines, but take 5 minutes to get their junk into the bins and bring the lines to a screeching halt.
My last flight, coming home from WDW last week, had a funny one. Two people ahead of me in the line was an average-looking business woman with a laptop case. She put her shoes and jacket into one bin, then tried to get her shoes into the same bin, but they kept falling out; finally, after replacing them about 4 times, she reached across 3 people to grab another bin for the shoes. Meanwhile, she had put her whole laptop bag into a bin, without taking the PC out of it; naturally, I assumed there was no PC in it, and that it was just a briefcase. But when she got to the metal detector, the agent asked her, and sure enough, there was a PC in there, so she pulled it out and put it in a bin - but she didn't zip the bag shut. On the far side of the metal detector, she picked the bag up by its handle, and its contents spilled out all over the floor - at least a half a ream of loose paperwork. It took her about two minutes to pick it all up and shove it into the bag, then she preceded to put herself back together right there at the end of the belt, blocking the belt and the line behind her. Finally, the agent asked her to move down, and those behind her were able to get their bags off the belt and proceed. All of this was probably due to her being an inexperienced flier - but she was in the lines that were for travel experts.
So I don't blame the TSA automatically when I see someone complaining about how "dictatorial" they are; I figure those complaints usually come from someone who is unfamiliar with the rules or is outright breaking them.