Zeal : That's whats surprizing. To the naked eye we see nothing. But change that, go into the micro-world , thats where the tip of stylas contacts the LP , lots of different factors affecting reproduced sound.
Of course, what one is hears is dependent on what you own and the condition/quality of the playback hard / softwear.Nevertheless, the reported experiences of tens of dozens of persons that either use steam solo in combo with RCM's all acknowledge the improvment. Even "Stereophile" acknowledges the difference, for whatever that matters.
In summary, All record cleaning fluids leave a sonic fingerprint that Steam Cleaning with the purest H2O available removes. Personally, I have discovered the scientifically cleaner the H20 the better the over-all results. All the Best