Not going into any details, but I know a person who does WETT certifications on a regular basis and some of the horror stories he has told me would make a clowns shoes curl. Rusted out stove pipes, clay chimney liners disintegrated, cracked fireboxes, improper clearances such as stove pipes virtually touching trusses or wall studs, you name it, he's seen it and people curse him when he won't sign off.