I asked that very same Question a few months ago!
I was given a line of Unix to type. I used it last night. It was an unmitigated disaster!
I had a months worth of old Time Machine backups that I wanted to retire. I'm talking about about a half million worth of old files. All but the last 10,000 or so were eventually deleted. But it wouldn't delete! So I used the "sudo" command several months ago.
It deleted the current files
😱, the latest copies the current work files.
😱😱, backup files on 2 different flash drives
😱😱😱 and messed up the rest of the Time Machine backups.
😱 It also messed up the System Files in the Internal Startup Drive so badly I had to reinstall Snow Leopard.
😱😱😱😱
After the reinstall I instantly copied the deleted files from undisturbed Flash Drives that weren't touched. (I always have 4 Flash Drives plugged in a Hub; 2 Data Drives, backed up daily but not just yet
🙁 ; 2 Drives that contain what best be called "Etc", "Everything Else" files. Backed up irregularly.)
I did what I've done before. I changed my Startup Disk to an External Drive and rebooted Leopard 10.5. Emptied Trash - 250,000+ files
🙄 - and switch back to Snow Leopard.
I spent the rest of the night repairing the worst of the damaged files.
I'll be working the rest of today bringing the nuked files back up to speed.

REALLY needs to work on making deleting large amounts of obsolete files easier.