Surfactants reduce surface tension, which helps a solution spread out into a thinner layer and wet smaller surface irregularities. This makes the solution more resistant to being vacuumed off and in fact vacuuming is insufficient. Rinsing AND vacuuming is required to remove it.
Unrinsed surfactants leave residues. Try washing your dishes in soapy water and vacuuming them dry without rinsing. Good luck, and don't invite me to dinner!
If the surfactant residue on an LP isn't removed it forms a cushion between vinyl and stylus. The first thing to suffer will indeed be the highs, since their groove modulations are the smallest. If the stylus can't see it you won't hear it.
Low level details and overall amplitudes also suffer, but the audibility of that tends to vary with the ability of the entire system.
Rinsing (at least twice) with extremely pure water and dedicated brushes, with a vacuum pass using a dedicated wand after each rinse, usually removes this residue. There are exceptions however. Some old (pre-MoFi) RRL Super Vinyl Wash contained a leave-behind lubricant. Water would not rinse it away, a complete re-cleaning was required. The orginal Disc Doctor cleaner was also notorious for being difficult to rinse.
***
As regards a cleaner, better-rinsed record sounding "drier", "brighter", "thinner" or any other adjective that doesn't imply "closer to the original", that's just personal musical taste overruling reality. By definition, only the cleanest, most completely rinsed and residue-free groove can allow a playback stylus to precisely retrace the path of the cutting sylus. Any residue, by definition, introduces a form of distortion. If you or your system prefer that distortion to the reality of a cleaner groove, okay, but it should be acknowledged as such.
Harrumph! ;-)
