Low-effort riddles have always been an headache. They waste our precious time and even more precious, efforts. But...
What are Low-quality riddles?
In PSE terms, they are those riddles which have multiple good answers and OP is just asking us "Tell me, what I am thinking." That's not how riddles should be. It should have a definite answer. They should be like "You'll know when you find out."
One thing I'd like to note is that easy riddles are not always low-quality riddles. Both of them are quite different things. A riddle can be quite nice even if it's easy. But we have also seen some easy puzzles with the riddle tag when they should have trivia tag. According to wikipedia, "A riddle is a statement or question or phrase having a double or veiled meaning, put forth as a puzzle to be solved." And I think the riddles should always be posed in way that they have double meaning but a single answer. But we understand if the number of answers increase to three, don't we?
What is the solution?
I think that we are handling these kinds of riddles in quite nice way and we should keep doing that. So I don't think we need to change our way of viewing these kinds of riddles. We can downvote when we need to and we can flag too. But if we are downvoting, we should always leave a reason of it. They will find out about their mistakes and maybe learn from them. That's why they are here, I suppose.