Mass probing services
I think this is the only time I've seen these used correctly - i.e. for a specific test that then results in something actually being done to resolve it rather than completely ignoring the end users who are the ones who end up having to pick up the pieces, possibly with the privilege of paying for them too.
This does not change my opinion that the primary 'benefit' of these services is to enable rapid botnet deployment and mass hacks.