Eostresh,
Just so you know, in some cases it doesn't matter if you can hear a bottom. Tegib's video is an example. He is sailing his tops and dealing bottoms straight to the table, so the cards dealt straight to the table can and usually do sound differently, whether they are tops or not. In other words, they can sound different because they're being dealt different.
That being said, if you are sailing bottoms and the sounds are night and day different, that's a problem. Also, and something that never seems to be mentioned, even if they are being bottom dealt to the table, they need to sound the same as tops being dealt to the table. What I mean is, if your cards sound one way when dealing to yourself off the top, then one hand you pick up the deck and the cards dealt to you sound way different (from dealing bottoms), that's not good.
Just stuff to think about.
Tegib,
That is great work and a pleasure to watch.