In what way...
Some people have trouble building, while they might have been doing it for a long time, their builds aren't all that great but still works enough that they believe that it's all good and "lock" themselves into "my builds are fine" mentality.
For build-up, if your coil has crap on it, you need more power to get the liquid to vaporize, so you end up increasing the temp if you're in TC mode.
Hotspots is pretty self explanatory... if your coil doesn't heat evenly across, you can end up overcompensating to get any vapor coming out, so you're overheating that hotspot as the coil isn't heating up in a balance way all across the wraps.
Chocking the coil with cotton, too much cotton, the heat transfers to the cotton instead of pulling the liquid through... so instead of the liquid vaporizing outside the coil's surface out of the wick, it's going towards the inside of the wick. So vapor is "locked" within the wick, you need to suck harder to force the vapor out, and so, you increase the temp instead without realizing that you're adding to the problem you're actually having.