The fact that this rate of missed attacks may be acceptably low although we cannot actually verify it also gives IDS systems some credence characteristics.
On the other hand, cryptographic products seem to have many characteristics of credence goods and few characteristics of other types. You certainly cannot tell before you test it that such a product will operate as advertised, so there are probably no characteristics of search goods in these products. And because it is expensive and difficult to verify that the encryption provides strong protection to information or that a digital signature is really difficult to forge, even after it is used, cryptographic products show more characteristics of credence goods instead of experience goods.
This uncertainty in quality that is characteristic of credence goods can lead to unusual results: prices that are lower than expected and are fairly uniform, even in the face of significant quality differences.
If consumers of a product cannot easily distinguish between high-quality and low-quality goods, even after they have consumed the product, we should expect that vendors cannot easily differentiate their products from competing products. In this case, we should expect prices of competing products to be roughly the same.
Consumers will not be aware of the deficiencies in low-quality products, so producers of low-quality products will tend to overcharge for them. Similarly, competitive pressures will keep down the price of high-quality products. George Akerlof first described this situation in 1970 in his classic paper ´The Market for “Lemons”: Quality Uncertainty and the Market Mechanism´, and eventually won the Nobel Prize for Economics in 2001 for his work in this area.
In the worst of these situations, the low-quality products will actually drive the high-quality products from the market as vendors of the high-quality products refuse to sell their products at the low price that the market forces upon them. Standards like Security Standards for Cryptographic Modules (FIPS 140-2) are designed to avoid such market failures and provide an indicator to customers that they are buying high-quality cryptography.
Such products are guaranteed to be the modern equivalent of snake oil made from Chinese water snakes.