Disclosing the permit status honestly in the property condition disclosure statement is what keeps the sale moving, since a buyer who discovers it during a $400 to $600 home inspection after conditions were supposed to come off is far more likely to renegotiate or walk away.
The buyer pool narrows slightly to those comfortable with an unpermitted space, often an owner-occupier who values the extra living area for themselves rather than an investor counting on the rent, but that pool is real and a fast sale is still achievable within it.
Pricing an unpermitted suite correctly, rather than as though it were legal income, is what actually determines how quickly it sells. Get your hand-reviewed valuation from Joel Dyck.