tweak, do they realy bring improvement?

Hi folks, do tweaks (anti-vibration devices, cones, CD-demagnetizers, tuning strips and adhesives etc.) really bring improvement to the sound, or is it just an alteration of sound what we hear? I think a unit (be it a preamp or CD-player) still have the same sonic characteristics (the nice and the nasty ones), even if tweaks are being applied. Audiophiles are getting excited when they hear "improvements", but often those improvements turn only to be a difference in sound. In my case I think my system is sounding best when no tweak is applied.

Chris