I believe that location is a huge factor in whether a mobile home can be a good investment. I currently own 2 double wide mobile homes and wish i could buy 100 more. I paid 26k for one that was a 2006 model on a decent piece of property and a 2004 model for 29k. Total investment was around 30k for each and they rent for $750/month.
In Panama City Fl, where i invest, finding a house that will rent for $750 on the mls will cost around $75k-100k and a mobile home could be half of that, so if cash flow is your main focus a mobile home can be a great investment.
One of the main issues with purchasing mobile homes in financing, very few banks will loan on a mobile home and you have to jump through hoops for the few that will. I circumvented this by just paying cash for my two. Also insurance can be rather expensive depending on location, here hurricanes are a threat so the insurance on a mobile home is more expensive than most SFRs.
So dont be afraid of a mobile home because they can be a great investment.