I take issue with your premise that questions should not be asked. They can be asked, if they fulfill the requirements listed in https://superuser.com/help/on-topic and https://superuser.com/help/dont-ask.
If the question or answer are outside the scope of SU or a duplicate or otherwise questionable, flag. Then the answer will be deleted or likely downvoted anyway. The problem ends here (most of the time).
Now you have a question that is within the scope. In spite of this, you think that a question should not have been asked. Because maybe it goes against your impulse that someone should have shown a bit of research effort. (I share that impulse, BTW.) Or you have some other beef with it.
You read the answer. What do you do?
Here are some options:
Good and useful answer
If the answer is good, vote it up. No matter how much the question sucks. Somebody made an effort to turn something trivial into something useful. Show your appreciation. (Or don't, if you think they've wasted their time.) You can always spice up the question by editing it to make it more relevant. This also raises the value of a good answer. Of course you need to respect the OP, but if the question is greatly improved, I don't see how anyone could object.
If you have the time: Edit to improve. If you disagree or find a different solution, post your own answer. If you find the answer valid but poorly researched and if you don't have the time or inclination to edit: leave a comment or downvote. If you can't be bothered to do any of that, then don't. Move on to something more interesting. Ignoring something is also a way of punishing it.
Some further musings (skip if already bored)
I've been on this site for a while now and the general consensus on stupid questions and answers is to have some kind of serenity about them. And about people who ask them and who can't be bothered to use Google. Further reading on MSO: Embrace the non-Googlers and Is LMGTFY frowned upon?.
You have to know your own limits; you need to decide where to draw the line. There is a lively debate in the comments and in similar questions that is never going to end on MSO, if you read the linked MSO questions to the link above. There appear to be 2 camps: those who say "let them ask and answer as long as it's useful to someone", and the others who say "don't waste my time with trivial stuff" and who will punish you if you go against it.
The general rule is to help as much as you can, even though there is no immediate reward and it may not be obvious to you why it might be necessary to answer the question. Remain polite at all times.
On the other hand, downvoting someone - who has shown no research effort or has done a poor job of explaining something worded - is perfectly legit. It actually says so when you hover over the downvote button.
It's similar to democracy: If you like something, vote for it. If not, downvote. (I'm Swiss, we do a lot of voting here.) The vote may not go the way you wanted it to go, but there was a vote. Accept the result. What you like or dislike is not for us to decide.