It gets to the point I am not sure what to think. Yes, one hears lots of conflicting stuff about this. However, you've come to the right place to get to the bottom of it all. Here's the deal. Quantum field theory takes quantum mechanics and special relativity into account, and it's a great theory of all the forces and particles except gravity, but it ignores gravity.
General relativity is a great theory of gravity, but it ignores quantum mechanics.
Nobody knows how to reconcile these theories yet. Now, the reason I'm telling you this is that quantum field theory and general relativity have really different attitudes towards the energy density of the vacuum. The reason is that quantum field theory only cares about energy differences . If you can only measure energy differences, you can't determine the energy density of the vacuum - it's just a matter of convention. As far as we know, you can only determine the energy density of the vacuum by experiments that involve general relativity - namely, by measuring the curvature of spacetime.