There is an option at “Front end search settings”->”Post Tags”->”Display posts/pages/CPT as results, which have no tags?”. It reads “When turned OFF, any custom post type (post, page etc..) without tags will not be displayed as results.” Default is off.
I have two tags on my search page, but whether this options is on or off, and the user unchecks all the tag checkboxes, the results list shows all posts instead of none. What should happen: no posts should display.