Hector, please don't paint an entire indusrty with such a broad brush. FYI there are a lot of very sensible manufactured home investments out there right now. If a rent/lease park/community is in the path of progress MH's can realize reasonable appreciation not depreciation.
If the MH is in a resident owned community i.e a condo conversion, subdivision, or planned unit development (PUD) or on a private lot/parcel they also realize fair market value. About the only time they will not hold up their value is when and if the MH is on a 250k private lot/parcel and the nearest comp is in a 50k MH park/community.
To prevent this from happening a buyer of a lot/parcel could choose to purchase a "Modualr" home instead of a "Manufactured" Home whereby they would then be able to use local comps in the same neighborhood instead of having to use comps from the nearest MH park/community.
Where I caution my clients is in purchasing a MH in an old run down park/community with lot's of old PRE HUD "Mobile" Homes/trailers. This is where the bad rap comes from and how folks can get hurt if they're not careful.
There are folks in this marked who don't necessarily want to buy a home or a condo for one reason or another. Maybe they don't want to share a common wall and grounds with others because they want their own privae driveway, yard, storage shed, etc.
Then there are those who don't want to be shackled with a mortgage, taxes and all the other responsibilities of a property mortgage. I work with seniors/Baby Boomers regulary who are downsizing after 40 years of home ownership and love the idea of purchasing a MH in a nice upscal rent/lease community or resident owned development.
As a Manufacture home Dealer & developer and a real estate broker I want what's best for my client. Not what's best for me. I try to educate them on the positive and negatives of both lifestyles and will spend time showing both. But I would never discourage someone from purchasing a MH if that's what they truly want. In fact that's a good way to push a client away from you in a hurry.