I used to use the VLQ flag on Ask Ubuntu, and it seemed to be working OK, but starting about 1½-2 years ago I started repeatedly getting declined/disputed reviews on my VLQ flags, so I almost never use the VLQ flag anymore except for complete nonsense.
Different Stack Exchange sites seem to have different policies about the correct usage of the VLQ flag. I still use the VLQ flag at Android Enthusiasts Q&A, and I haven't had any problems with it there. I think the VLQ flag works at Android Enthusiasts because so many people like to type strings of random letters on their phones and submit it as an answer. I use the VLQ flag at Superuser Q&A, and it works most of the time, but only because I use it only in extreme cases like answers that are just a bizarre geometric pattern of repeated text.
If an answer is a link only answer, I custom flag it as a link only answer, and that seems to be working OK. If it's a spam answer, I flag it as a spam answer, and that also seems to be working OK. If it's an answer that says to install some esoteric free Windows program that isn't spam, and even though I would personally prefer to use to VLQ flag that doesn't work, I have no choice except to downvote it and wait for it to show up in the review queue because someone else flagged it as VLQ or NAA and got away with it. Most of the time this method works too.
I have never lost the ability to flag questions, so this strategy seems to be working for me. I feel sorry for all the people who have to eat disputed/declined flags in order to make a wrong answer show up in the review queue, but I can't help them because the system doesn't work that way.
Last of all I have a recommendation - don't "overclock" the VLQ flag.