In modern English, the comparative/superlative for the word "bad" is indicated as worse/worst.

A number of years ago, it was worse/worse. When did this change?

It has not changed. See below:

http://www.jiskha.com/display.cgi?id=1165241783.1165245841

=)

Thank you for using the Jiskha Homework Help Forum, but I guess you didn't believe me yesterday! I gave you the "history" of this word.

http://www.jiskha.com/display.cgi?id=1165241783

Here's the entire exchange yesterday.