Garbage in / Garbage out is also very true.  When you enter data into your CRM database, take the extra time to do it completely and accurately, correcting errors as you go.  Using the Google Forms I’ve written about here, you can do an easy import of the information into these databases.  However, if the site visitor has entered errors (likely), then correct them before or after the import.  I like to do it in the Google Spreadsheet before the export to .csv.