The last post suggests reliance on "agencies" to achieve good, honest work in weatherization. I don't think that is the way.
Public display of customer reports might work. We might all belong to an affordable and more-informative Angie's List. With diligent reporting of satisfaction, or being wronged, a careful home owner could intelligently choose honest workers and consensus best practices. I have tried to influence Angie's List to entice fuller membership through low pricing, and reward of responsible participation. Suggestions include a Honored Member status, earning half-price annual fees, at not more than $20 per year. All new members are Honored Members, helping them over a barrier of uncertainty, where one must pay first, to see the value. Honored Member status is retained by responsible participation, say a combined number of five, in posted reports and referred new members. With five years of Honored Member status, it becomes permanent. I want Angie's List to succeed in this way, and welcome customer reports on my work. Good work, reported, is my investment in advertising.
Another solution is having self-maintained records of work well done. I imagine Google-like companies (several) setting up data warehouses, where the condition of our homes is a public record. Things that matter to society get recorded. Measures taken for energy efficiency are for the common good, and are included. Posting is voluntary, with rewards. The public record is a basis for home valuation at resale, and for more-favorable taxes and mortgage interest rates.