Advertising endorsements as a whole have the common characteristic that consumers are led to believe that the endorser is an expert or has particular knowledge to approve the product. This is not always true. Endorsements may be inaccurately reproduced; taken out of context; or supplied by individuals, groups or agencies supposedly unbiased but actually connected to the product. Problems also arise where the endorsement implies continued use or experience with the product but it has actually been based upon single, isolated, or infrequent usage; and where an endorser's assessment of the product may have changed but the advertisement is continued to be broadcast. Endorsements of children's products can have great influence on children who are particularly susceptible to sophisticated advertising practices; and endorsement of products which may be hazardous to health (pharmaceutical products, alcohol and tobacco) may have serious consequences.
Misleading advertisement endorsements include testimony by an allegedly independent testing agency which was in fact financed or controlled by the advertiser and the use of consumer surveys where the results have been achieved as a consequence of a biased questionnaire.
In 1997, the American Medical Association permitted a home health products company to place the AMA seal on its products in exchange for royalties for 5 years. This will mislead customers, to whom such seals would ordinarily imply that the AMA has tested the products and found them to be satisfactory.