I hooked up a hard drive and re-arranged my hard drive sata connections. I noticed there was alot of dust and cat hair around the connections when I plugged the plugs back in. The hard drives are working fine and everything is great. I could blow some air in there, but the motherboard is old and those sata connections have always felt a little loose/cheap and I don't want to break anything that's not broken. I am going to be copying my music files over to another hard drive. But now I am kinda worried, if there is dust or hair in the sata plug where the metal teeth touch and I transfer my music files, will some bits be lost and degrade my music files or alter in the transfer?

SATA interface uses CRC32 checksum on a very low level to make sure all data was transferred correctly. If there was any problem, you would be noticed by the operating system.

You don't necessarily get notified if there's something wrong, unless you check in the Event Viewer for errors once in a while.

I had this internal card reader that was malfuntioning. The symptoms were random slowdowns (of XP back then), and shutting down the PC took about 5 minutes. Turns out there were lots of errors logged for the card reader drives. But i suspected so many other things before looking at the Event Viewer... now it's about the first thing i look if anything's fishy.