This has been bugging me for the last couple of weeks now and I just can't figure it out. I seem to have acquired a squeak, or chirp, in my driver-side front wheel. It sounds like a really pissed off bird just chirping away as I go down the road. It gets faster with speed and only goes away if I apply the brakes (it sounds like I'm strangling a bird for a second and then stops) but then it immediately comes back when I take my foot off the brake.
I've taken off the wheel multiple times to investigate. The pads look brand new, the rotor looks awesome, there's a good amount of grease everywhere, there's no scarring on the back of the wheel. I replaced the caliper slides thinking that would help, and it did kind of. Now, instead of the chirp happening all the time, it only happens if I've been driving highway speeds (55-65mph) for some time and then slow to town speeds (35mph).
Also, I'm not sure if this helps at all but, the PO thought it'd be a neat idea to paint the front calipers with blue spray paint? However, it doesn't appear that they ever thought of masking anything off, including the piston housing.

I'm baffled. The noise gets so loud sometimes that it echos off surrounding buildings and I can hear it over my exhaust and my radio - which is kind of embarrassing. Any help would be great. I don't have much time in my schedule anymore to continually take the wheel off to look at it, and I'm tired of poking in the dark.
Cliff Notes For Lazy People:
-Chirp in driver-side front wheel
-Sound correlates with car speed
-Only appears after driving highway speeds (55-65mph) and then slowing to town speeds (35mph)
-Momentarily goes away when applying brakes but comes back
-Caliper slides replaced, but did nothing
-Everything else brake-wise looks great