How about excessive entrepreneutial/management fees profit, grred[/QUOTE
Somewhat of an extreme situation which really has little bearing on the generally accepted concept of the cost approach except in extreme situations. One would think, all things being equal. An informed buyer would avoid neighborhoods of that type like the plague. But your market might be different.
In many cities you can buy houses similar in style, appeal, GLA, bedroom, bathroom, school district, etc. however they differ in price by $200,000 to $300,00.
How about location, location, location within the city and same school district. Generally speaking. Not all neighborhoods within a city with same school system are the same. Pretty simple concept. There are many examples in the metro area I appraise in. Similar houses on similar lots. But the homes on the west side of town sell for 100k to 150k less than the homes on the north side of town and the homes on the east side of town sell for 50K less than those on the west side.. No difference in school system, access to amenities, built up etc. So what is the difference? Site value. Why is there a difference? Location, location, location. IMHO. A fairly basic concept when it comes to real estate.