High coverage does not necessarily imply test suite effectiveness, nor does it even guarantee that your test suite provides positive value.

But 0% coverage does tell you a lot about your test suite effectiveness.

Also, beware the person too eager to proclaim that high test coverage is not necessarily good!

Last time someone told me this was discussing process maturity during a job interview. I let the team slide with this answer. Found out their coverage was effectively 0 and their process maturity was "break everything until right before each quarterly release" and I was out of there before my first week on the job.