This page is an entry in the Key.

sky,
replacing or inserting different

Any photograph in which the sky is replaced, in whole or in part, for any reason, cannot qualify for the “Guaranteed TCQ” label under any circumstances.

Replacing or inserting a sky keeps the photograph from meeting multiple qualifications of the Trust Checklist.

A bright overcast sky can often appear completely featureless in photographs that qualify as TCQ; see the entry on blown-out backgrounds.