At least since four years and 15 months ago, a new rule was added all across the network known as Stack Exchange.
Comments must be at least 15 characters in length.
Some people have (had) figured out ways to break this long coveted rule.
Stack Overflow has 4225 comments less than 15 characters in length.
Server Fault has 94
Meta Stack Exchange has 288
Super User has 193
TeX - LaTeX has 57
English Language & Usage has 40
I also checked a few other sites, which tended to have less than 30. But when you have 131 sites, they sure can add up quickly!
As you can see, by searching through those comments, 99% of them are useless, not constructive comments. Plus they knowingly or unknowingly broke the rule! So even if you find one that could be left alone, I still wouldn't mind it being deleted. Just like how questions from 4 years ago were on topic back then, but can now be closed for a close reason that just recently came out.
How should we proceed? Should we just leave it up to individual users to go through and flag these comments for a mod to review and delete? Should the team make comments that are less than 15 chars available for automatic deletion on one flag? Should the team just run their own query to delete all of these and be done with them? What do you think?