The chief reasons for being in the splatter club are these:
ESSB, 99.99% of people using outboard audio processing gear with excessive bandwidth cause a lot splatter. ESSB is a menace practice on the ham bands.
I agree. I hear many stations running some form of outboard audio equipment, and they really sound terrible. Rarely will you find someone that gets it right. Most, try to boost the bottom and top end, and achieve nothing but mushy distorted audio.
Even without outboard processing gear; the biggest problem I've heard for years, it seems so many just don't know the basics. Simply turning down the mic gain would help so many. I've always been amazed at the guys you hear up and down the bands, running the mic gain wide open or running the processor too hot, mixing in tons of back ground noise with their signal.
If ops would follow one simple rule, a lot of objectionable signals could be avoided. If power is going out over the air on SSB when you are keyed down, but not speaking, you need to turn down the mic gain, period.