I am part of an organization in which there is contention amongst some very competent folks as to whether or not testing cross-browser behavior for JavaScript applications on virtual machines (for IE6/7/8, FF2/3, Chrome on XP/Vista/7) is reliable. This is using VMWare server on a Linux box host. While the discrepancies seen are few, there are cases in which it has proven difficult to tell if it is a product of virtualization or just different machine configurations. My question to the community is, what is people experience with this? Is there any credence to the claim that VM pose inconsistencies, or are they generally spot-on reliable? Can we trust them?