Presumably that includes handing databases over to 3rd parties who do imports?
If you do an import for someone you don't need to go through the database visually and read the content.
Most of the times I do not get to see any threads, posts, nor is there a need to even look up any personal msgs. The only reason you'd go to the public forum after an import is to view if the forum structure is there, if a thread loads and doesn't look broken and if the forum statistics look like things went fine.
A preview can be given to the owner of the site who can review the content - it's their forum after all.
I see no reason (for the imports that I do for others) to scan through a database, read content from threads, etc. It's all back-end stuff. And it's a courtesy towards those who trusted you with their database.
After all, if one is interested in the content, they can just sign up on the site when it runs live and read the posts.
This is also why I would do an import via a professional, rather than someone who says: this should be easy, I will do it for free or $4, trust me .. I won't resell your .sql on digitalpoint.com or flippa.com