2nd and 3rd harmonic distortion will cause bass to sound overy full, ill-defined and in extreme cases, wooley, mushy or fuzzy. In the mid-bass/ mid-range mild distortion can sound warm and full but at higher distortion, it can sound like a guitar fuzz-tone sound. In tweeters it can sound grating or eeky.
Boomy-ness is more a factor of over pressurizing or loading up the room. Bass likes to couple to large flat surfaces ie: wall and floors and in doing so (depending upon the length of the surface verses the frequency) can result in as much as a 12dB gain for that frequency (standing wave) thus the one note bass effect.
Thx, bobby you explain it much better than me. "Overly Full, ill-defined, warm and full, wooley, mushy or fuzzy" is more what I meant with regard to harmonic distortion....I like Gregm's "bloated" too.... how about "Muddy" LOL.
The difficulty comes when some may say that a correct sounding bass with very little harmonic distortion is "overly tight, dry, anemic, lacking warmth, fatiguing, tiring or thin" sounding.
Therefore some consumers will prefer a distorted speaker over an accurate one. Go Figure! It ain't even close to accurate music reproduction...but it sounds pleasant and they prefer it and they don't lack for bass!!!
Typical speakers can have upwards of 10% harmonic distortion at ultra LF (when played at high but not excessive SPL's)...not yours of course.