Loud humming sound when at speed, need help

I am completely stumped. Quick back story: I am working on my girlfriend’s 2003 Toyota Corolla. About a month ago her step dad replaced the brake pads but kept the old rotors. Since then, a humming/droning noise from the front that begins around 10mph and progressively gets louder with speed and has been getting worse and worse over time. The noise will almost entirely go away if your press the brake pedal. Her step dad had clearly never done a project like this as he had to watch step by step videos off youtube while doing the project and it also took him nearly 5 hours to replace 4 sets of brake pads. This was worrying news to me.

Today I decided to look at her car for her since I have intermediate mechanical skills. I noticed the clips that held the pads were slightly bent and just not sitting perfectly right. After removing the clips to replace them, I noticed a lot of build up under the clips where they sit. So I scraped the build up off and installed the new clips which now sit much better than the old ones. I then noticed a slight uneven wear in the pads. I measured the inner and outer widths using a set of calipers and noticed the outer edge was 0.3cm more worn than the rest of the pad. I also noticed her step dad did not use any grease to lubricate anything so I got to work on that and put grease at all the regular friction points. Hoping the new clips and grease would fix the problem, I went for a drive. Nothing has seemed to work, nothing has changed. Could it be the pads are now ruined? I would hate to have to replace them, they’re barely worn and a good set of Bosch pads. Could the pads actually be okay and it is actually the wheel bearing in the hub causing this drone/hum? I hate replacing things just hoping that’s the problem. Thanks in advance
Hey buddy, from the look of it, your brake pads sound like they might be fine, a picture would help. The outer edge of the pads are manufactured with a slope for most of the pads I've ever installed so I can't really tell from what you've explained if it's actually normal. If you don't feel vibrations or the noise doesn't change when you apply the brakes there are two things I could think of:

- Bad bearing, but at this point it would probably sound like you're driving a little cessna plane and the noise should of been there before the job
- Brake caliper pistons were near their end and he killed them when he compressed them to install new pads (it doesn't retract and holds pressure on the pads)