There are a huge variety of these homes. I've seen two which were excellent, looking more like a wood framed drywall home than a trailer. One in Oregon, one in California.

Great if we could develop alternatives to using the most known irritant chemicals in premanufactured homes. Last I heard formaldehyde is present in many pressed wood products. Plastic products outgas, especially exposed to sunlight. I hope our "greener" future will mean manufacturing more of our common goods with more bio-friendly formulations of what have turned out, over plastics' life cycle, to be rather bio-unfriendly substances.