This is for everyone's information.
My car about four months ago developed a severe brake groan noise coming from the front driver's side brake. Now I'm pretty good at automotive work and the first thing I could think of was that the brake pads weren't seating well with the brake rotor. So, I replaced the front pads and rotors. Well, one the brakes heated up, I got the same ridiculously loud noise. Scratch head and using the typical logic, I thought "maybe these particular pads and rotors (Myle) don't work well together. Even though I've used these before. So, I bought another set for the front, replaced them, cleaned everything and guess what? It still made the same noise from the same brake.
Wow! now I'm pissed. so, It must be the brake caliper sticking right? So, in my infinite wisdom, I replaced both front brake calipers, bled the brakes and I'm good to go right? Wrong. Same noise when braking. very loud.
So, now I'm thinking front driver's side wheel bearing right? So I replace the wheel bearings. Same freaking noise!!!!

What the @@<<<## is going on here?

Should I wait for everyone to take a few educated guesses?

No, I'll tell you.

The rear brake pads were so low that because of that, they were causing the front left brakes to apply incorrectly and cause that loud noise. So, I replaced the rear pads and rotors.

The reason I didn't change the rear pads and rotors when I did the front was that I ran out of time when I initially did the fronts and the noise appeared. I spoke with many of my mechanic friends and they all told me that I did exactly what they would have done.

I laugh now, but I would never have thought that the low rear brake pads would force the front brakes to do that.

Lesson learned. Check and replace them all (if the rear required it).