plugins which affect database tables… the tables or columns are not deleted after the plugin is uninstalled.
Also, there was an ical or calendar issue by @alfred, which also got into this plugin as a feature… which then became known as a cleaning job.
the sessions table was causing 50mb of data for me, there is a fix i that to be able to empty the sessions table.
the plugin will soon be a collection of cleaning jobs (fixes/restore to default) for each issue anyone has encountered and reported.
ContentCleaner is fine in functions as far as i know but the layout, styling, some functions and the readme are not fully updated so use at your own risk.