My beard sucks and it basically has most of the bad attributes a beard can have: bald spots, gray hairs, thin patches, regions of different colors, random "pubic" hair quality hairs (often in white).
The hairs I have on my lower lip are nearly blonde, and combine that with the fact that it's fairly thin and it makes the area look even thinner.
The right side of my face grows thicker and higher up on my cheek than on the left.
I don't think I have a place that grows faster than the other place, but even if it did: so what? Just run clippers through it every 4 or 5 days and you'll never notice.
One thing that took me well over 10 years to figure out is that my face is not symetrical. I cannot trim the left edge to match the right edge. It looks symettrical from the front but the sides look different from each other. I finally figured out that my jaw isn't symetrical so it's impossible for me to trim both sides perfectly identical.