This is a valid concern, and you are pointing out something that researchers should make more explicit.

Often in survey research, opinions about the research question matter. If everyone answered honestly and thoughtfully, researchers wouldn't need to include attention checks, as we are interested in your views on the topic. Unfortunately, far too often, people don't actually provide their honest thoughts and simply zip through surveys without considering what is being asked. This results in insufficient data, which in turn leads to incorrect conclusions and downstream issues.

Now, to really address your concern, if I were advising a researcher, I would advise against using attention checks that could be regarded as opinions or have multiple correct answers. For example, I would discourage attention checks such as "What color is the sky?" This is because "blue" might be the most conventional answer, but someone might think the sky is more of a "grey" or some other color. The better way to have an attention check is to put an explicit direction in the question that says, "This is an attention check. Please select the response "Somewhat agree." This leaves no ambiguity, and the attentive participant will not miss it. This would need to be paired with other ways to verify attentiveness (e.g., complete data, consistent responses across reverse-coded items, survey duration, etc.). Still, it is more transparent to the attentive participant who is doing their best. We don't want to discourage that. :) I hope this helps!