First, most alopecias are not a gradual progressive hair loss. Most, including androgenetic alopecia, develop in spurts and then stop. There may even be some improvement for a short time before the hair loss begins again. Someone using a hair growth product might falsely attribute this slow down or temporary reversal to the use of the compound. Once their letter is on file there is no way they can retrieve it should the long term use of the product reveal that it is actually entirely worthless.

Second, people who want to believe will believe. When real drug companies test products for hair regrowth they run at least two methods of analysis side by side. One method is entirely empirical evidence. They mark an area on the volunteer's head and count the hair density in the area before and after treatment to see if there is improvement. The other analysis method they run is more subjective. They give a questionnaire to the volunteer and ask how the volunteer tester perceives the drug is working. Most human trials of drugs for alopecia are classic double blind studies involving a group that receives the drug and another control group that receives an innocuous placebo compound. No one knows whether they are using the drug or placebo. Frequently what is found is that volunteers on the drug or placebo indicate they believe they have regrowth of hair, but when comparing their positive comments to the hair count/density data it is revealed there is no actual improvement and there may even be a deterioration. Call it optimism or an over active imagination, it is an important factor for professional advertisers and scam artists.

Third, one or two people may really have hair regrowth, but out of how many that tried the product? Testimonials from five people with hair regrowth out of ten people who used the product is a 50% success rate. Testimonials from five people out of a thousand who used the product is a 0.5% success rate.