"I took it and it didn't work so it's a fake placebo drug" - wow, your scientific method is flawless, have you considered a career at the US Department of Health?

Maybe you had an inflammation-induced pain. That would explain why ibuprofen helped, and paracetamol did not.

I have a counter-study with size n=1: I did all my recovery from tonsilectomy on paracetamol and definitely noticed it working. That was however on the maximum safe dose.

(one of the major problems with paracetamol is that the effective dose is only a few multiples away from the dose which starts to cause liver damage! It is by a long way the most dangerous OTC drug)

You're partially right compared to placebo only about 5% of people are painfree over the effect of a placebo when taking paracetamol.

Paracetamol got it's start as replacing the more effective but much more dangerous and withdrawn drug Phenacetin.

Why don't people notice that it's such a small benefit over nothing? Well because placebo effect is quite good for pain and pain is usually transitory anywhere..if you have a tension headache you're probably going to aim to relax. Turn away from the screen or even have some caffeine and those are more effective than paracetamol!