I disagree, although I take the point about UFOs! For example:
If OSR is a dimensional change, then some kind of micrometrology co-ordinate measuring machine might be able to measure it. This is a computer controlled device that measures the physical geometry of an object using, for example, an optical or standing wave probe. It can measure in microns (1/1000mm). There may be other more sensitive devices.
If OSR is a change in colour or appearance, then that must presumably be caused by either a physical or a chemical change, in which case it could still be measured by, for example, a mass spectrometer, which can be used to analyse the elemental and molecular structure of an object. I'm sure they tried to teach us about those in Chemistry lessons at school!
I'm not suggesting that such measurements are practical however, just theoretically possible.