CMB/CMV happens when variations in responses are caused by the instrument rather than the actual predispositions of the respondent. If measures are affected by CMB, the intercorrelations among them can be inflated or deflated depending upon several factors.
One of the simplest ways to test CMB is to use Harman's single factor test, in which all items are loaded into one common factor. If the total variance for a single factor is less than 50%, it suggests that CMB does not affect your data.