After deleting a user I then visit a View that would have referenced the deleted user and the result is a WSOD in user.module line 2665. I suspect the code issue is that $account->content is NULL for the deleted account and then the $build += faults because $build would be NULL. However, why would the function user_view() be called for the deleted account?
The problem is quickly resolved by clearing all caches.
I dunno if the problem is with core or some of the other modules I am using.
I use Display Suite to format the user for display.
I also use Views Cache Bully to cache the faulting View.
And I also use AdvAgg to do further caching, though that seems unrelated.
The actual error reported is...
PHP Fatal error: Unsupported operand types in .../modules/user/user.module on line 2665