Tape sampling is the most common technique used to test surfaces for mold during a mold inspection.
This method is non-invasive and will not damage materials or surfaces.
Tape sampling is meant to be used for qualitative rather than quantitative analysis.
Samples may be taken in each room or area where there is apparent mold growth.
When different types of mold present, as evidence by different colors, each can be sampled separately. 
Visible mold on different substrates and building materials may also be samples separately.