How to discount a house for being ugly when doing an analysis?

[Coley Mitchell]

I'm looking at a house tomorrow as a potential next value-add project (either flip (primary) or BRRRR (secondary)) that can only be best described as "ugly." Was built in early 60s and if I had to categorize the style would say poorly executed art-deco. It is smooth stucco with a flat roof. It is definitely VERY different than the typical ranches and craftsmen style homes in the area. That being said, the numbers are interesting. In my initial analysis I factored in a 10% discount for being ugly. Is that enough? Anyone have experience trying to flip an ugly house in a great area?