TLIK – I agree with you that people have to be careful about not getting too caught up in labels. The main places where I see these terms used is on SYAS & JWED & shidduch resumes. In all of those places, people have the opportunity to explain what THEY PERSONALLY mean by the term.
Personally, even though I describe myself as Yeshivish, I won’t write off someone who considers himself “modern Yeshivish” or “Modern Orthodox Machmir” without first clarifying what he means by that. However, if someone checks off that he is “Modern Orthodox Liberal”, I KNOW that he is not for me. And honestly, the “modern Yeshivish” guys are rarely for me. Even the “Modern Orthodox Machmir guys are rarely for me. So labels do seem to mean something, even though one should be open-minded enough to look beyond the label at the person.