What junk cleaning tool for iPhone is good?
I found a promotion on Macupdate today which just happen to be a cleaning tool for iPhone. Take a look here http://deals.macupdate.com/deal/16184/macgo-iphone-cleaner
On the whole, I would avoid using such software. It should be used only in extreme situations, and then you might consider resetting the device to factory settings and reinstalling the apps.
Try the suggestions mentioned in the below article -
How to clean documents & data and junk files from iPhone