From Grammerbook.com - A common error in using adjectives and adverbs arises from using the wrong form for comparison. For instance, to describe one thing we would say poor, as in, "She is poor." To compare two things, we should say poorer, as in, "She is the poorer of the two women." To compare more than two things, we should say poorest, as in, "She is the poorest of them all."

SO... in this case, it goes from bad to worst.
One = bad, Two = worse, Three or More = worst