I'm using Gravity forms to include the custom fields I created in People Lists to the registration form. With it's User Registration add-on Gravity Forms lets you map the fields you created in the form, to available meta fields. In my list, I can see several fields that I added, then deleted. So I assume the plugin isn't fully deleting these. If you're like me, you don't like junk that should be deleted bloating your database. I'm not a developer, so I'm not totally sure of myself here, but this seems like a bug that needs fixed, so those things get completely removed. Thanks.