I'll bite...

If you are just looking at thread titles in a list with a view to working out whether to open them or otherwise trying to establish what they are about, I would be inclined to agree with Clinton in that overall, a well considered thread title is far more helpful.

On the other hand, if as lamarca was, you give consideration to people searching for information or ideas that they may like to seek out (or ignore) certain types of threads, prefixes can become important because it gives the computer a means of helping you (the poor old computer does not understand English however well written but can understand rules like ignore threads with "BS:" in or look only in threads containing "REV:").

I'll leave it with the thought that when used in combination with filtering, provided prefixes are well thought out and applied consistently, they could become a powerful tool.

Jon