Do tube dampers improve sound?

I guess if I have to strain to attempt to hear a difference
I write it off as a bad investment. I put Herbies tube Dampers on my entire system (all tubed at that time) and failed to hear any improvement. The other thing I noticed is that the dampers used on my kt 90's got sloppy with use.
They are sagging on the tube and not really holding onto the tube. On the other hand herbies grungebuster is the best tweak I have ever tried. For 16.00 it made a large improvement in the sound of my cd's.

Steve, thanks for allowing me to return the teflon tube dampers and exchange them for the nickel dampers. You have integrity that is too often missing in high end audio.
I also enjoyed talking audio with you for at least an hour
when I purchased your grungebuster. Your grungebuster was the most effective tweak I have ever tried and an incredible bargain. I had upgraded my preamp to the CAT Ultimate MK2 and my DAC to the Audiologic 24MXL just before purchasing your grungebuster. That tweak was a greater sonic improvement that the $11,000 upgrade! Thanks again.

Bart