Run the property both unleveraged and with your proposed financing. That shows whether the apartment itself works or whether the result depends on debt terms. Then vary the financing cost, vacancy period and rent. If a small change turns the cash flow negative, the appreciation thesis is...
I wouldn’t give fall-through rate too much weight by itself. A low figure can reflect easier properties or cautious seller selection rather than stronger handling. Ask what they actually do when a survey, chain or finance issue appears, and how often you receive an update.
My practical approach...
That is a fair counterpoint to Naomi’s earlier suggestion. Define enough structure to avoid random collecting, then let actual listings challenge it. If every example needs extensive exceptions, the categories probably need revising.