Looking for studies about user bias against dashes in domains

[NameFu]

I've been telling end users that having a dash in their domain can scare away potential customers and degrade their general reputation as a professional business....especially when the dash isn't necessary.

Are their any studies about this topic that I could reference? I think that it's mostly a no brainer that dashes *usually* lower the quality of a domain, but it would just be nice to have studies to compliment my advice.