Cookies are such small text files that they don't use up disk space to any significant degree. Browser cache files are the space hogs.
Clearing out tracking cookies is a good idea, but you may want to make an exception in CCleaner or in your browser, not to delete cookies for specific websites you want to keep logged into.
Cookies do on occasion become corrupted. But, generally, will be apparent due to login issues. In which case, you just delete them and log back in.
BTW, if using Firefox, there is a handy extension
Self-Destructing Cookies that delete tracking and cross site marketing cookies when you close your browser tab. You can whitelist sites such as RV.NET to keep you logged in.