Today I came across this answer, while searching for a duplicate.
(For those of you that do not have the privilege of being able to see the now deleted post, and for which my link seems broken: )
I am not sure if the answer originally was flagged as link only, IIRC you can only do so if it shows in the low quality queue, the option to flag as such does not show up when clicking the 'flag' link:
The link is now broken, and I flagged this for moderator attention.
We should try and get the "This is a link only" option added to the list above, in a way that they get handled the same as reviewed answers marked that way (triggering deletion?). Possible (re-)inserting the answer in the low-quality review queue.
Assuming that what happens with reviewed questions where "This is a link only" has been selected multiple times, is that they automatically do get deleted. Then the addition of the "This is a link only option" to the flag possibilities would have helped pushing this answer out of the system.
Get some mechanism in place to check on links in answers that were marked Link-only at some point and if the link is broken on two consecutive checks, have the system reinsert this in the low-quality review queue, probably resulting in deletion.
Just downvoting the answer seems a bit ineffective, selecting that it is very low quality is a bit vague for this specific problem (but might result in the item going in the review queues, I am not sure). Or is there any other alternative that doesn't involve the 'heavy hand' of calling in the mods, to get this cleaned up?