Why disclosure matters more here than with cosmetic issues
Mold is treated as a material defect when it's known and significant, which puts it in the category of things a seller needs to disclose rather than something that can simply be priced around silently. Getting this wrong exposes a seller to real legal risk after closing — this is a genuine case for a real estate lawyer's advice specific to the property and what's actually known about the mold, not a general rule to apply casually.
That said, disclosing a known issue doesn't mean the house can't sell — it means the sale needs to be structured around accurate information, which as-is cash buyers are generally set up to handle.
Getting the source and extent actually assessed
Mold is a symptom of a moisture problem, not usually the root cause itself — a leaking roof, poor grading, high humidity, or a plumbing issue is typically what's feeding it, and identifying that source matters as much as the mold itself for anyone evaluating the house. A qualified inspector or environmental professional can assess the extent and likely cause, which gives both the seller and any buyer something concrete to work from instead of a guess.
Remediation costs and requirements vary enormously depending on the extent and location of the mold, which is exactly why a professional assessment matters more than an estimate based on visible surface mold alone.
Why an as-is cash buyer can be a realistic path here
Buyers who specialize in as-is purchases are generally comfortable pricing a house with a known, disclosed condition issue like mold, since that's the model they work in — the alternative, a traditional listing, can be genuinely difficult with mold disclosed, since many retail buyers and their lenders will hesitate. Getting the issue documented and disclosed honestly, then working with a buyer who deals with this regularly, tends to be more realistic than trying to remediate everything before selling.