If you think about it, it is a kind of ridiculous idea that you would need super-sensitive equipment to determine if some cheap device would interfere with the workings of some other relatively cheap device.
Do you need sensitive equipment to see if something is totally destroying performance? No. But arguably by definition, you need the ability to reliably measure at or below the noise floor in order to determine if some emitter is putting out interference that will raise the noise floor (thus degrade performance).
Note also that not all measurements are about interference. Antenna patterns and such you just want a more accurate measurement.
