Avoiding Validation Errors with WYSIWYG Editor

I am supporting a site that was put together by another company.  A lot of what they were supposed to do is half complete.  For the part I am looking at now, they decided to go with an old JavaScript WYSIWYG editor instead of using the tools provided with Sitefinity.  When anyone tries to update the data involved, they get a potentially dangerous data from the client error.  I am in the research phase right now to come up with the best solution. 

All of that to ask the question - does the RADEditor take care of this when posting back marked up content?  The site deals with confidential information and I would rather not have to turn off validation if it can be helped, as that would force me to do a lot of extra work to validate it myself and I could miss something.