As mentioned by Ed Finkler, there's a list of signs your PHP needs refactoring from Soledad Penades.

I have had to go through a php application recently which has given me more than one headache and has required me to use all my possible patience. While working with it, I thought This is good material for an article, so that nobody else does the same in the future, and nobody else will need to experience the same displeasure as I have had to.

So here are the signs your PHP application needs a serious refactoring, right now

Included in the list are things like:

• Uses global variables
• Everything's an array
• The neverending switch
• Interface inconsistency

It hits on one of the thing that bugs me too, the problem of "Brackets galore" - so many subarrays that you have to resort to three or more sets of bracketed keys to get to the value you want. It's bad enough trying to follow someone else's code without having to "trace down" an array to figure out which of the values they're talking about.