The lemons problem theory demonstrated how asymmetrical information can create adverse selection and how it can create negative consequences for market efficiency. First, buyers will place more emphasis on price than quality because of the uncertainty about the quality of the item for sale. As such, buyers overstate the proportion of products, or investments, that will perform below the average quality levels. This leads to a market in which both buyers and sellers end up worse off in terms of quality and price.

Furthermore, the lemons problem helps to explain the role of quality assurance techniques such as warranties, quality control and return policies in moderating the impact of the lemons problem on market efficiency. Quality assurance techniques help to reduce adverse selection and increase market efficiency. Quality assurance techniques can also help to reduce the costs of marketing and selling products/investments. For example, warranties on a product can help reduce customer's perception of risk, thus making them more likely to purchase the product. Additionally, in an investment context, the quality assurance of external auditors and other financial professionals help to reduce the customer's risk perception and increase market efficiency.

In conclusion, the lemons problem theory showed how asymmetric information can lead to market inefficiencies due to adverse selection and highlights the role of quality assurance techniques in reducing these inefficiencies. The lemons problem theory has had a profound impact on the understanding of how asymmetrical information affects markets and the role of quality assurance techniques in rectifying market inefficiencies.