A large log file mostly indicates that a program (or your system) has some problems that need to be resolved. Large log files can be deleted after inspection. If you do have a problem and want to delete the cache of some specific programs, I suggest you to click on the folder icon and search for that program and delete it this way. This will not save you some precious space on your disk. If you delete it, the program will not only start slower, but will regenerate the cache files again. Cache files are what makes your programs load faster and perform tasks faster. I do not recommend you to delete your cache files.

the cleaning option was just a handy extra feature. I wrote this app just for fast analysing purposes. A list of all scanned directories can be found here.