People pay what they value something at. Soda for example costs maybe $0.05 to fill up a glass in a restaurant. Yet people pay $2.00 for sodas in sit down restaurants. Just because something has a high profit margin doesn't mean something's dishonest. It just means you found a successful product. It would be dishonest if they were telling me I was paying for Soda and instead getting some inferior concoction, but when a product is clearly labeled and the consumer agrees to pay a price for that product, it isn't dishonest.
Also, a lot of times businesses will lose money a in certain areas like when they sell you your phone under a 2 year contract, expecting to make that money back from services like this. Is it dishonest for them to sell me a phone at a loss and make money back by charging more for texting? Dishonesty would be if I went to best buy and they tell me that monster cables are amazingly superior to the $5 cables I can get from monoprice, but best buy simply selling monster cables for $50 is not dishonest, even though it's not worth that money, because they sell their TVs a lot lower than competition and expect to make it back on such accessories and service plans. That's not dishonesty, that's me being an uniformed consumer.
Funny you should mention Worst^H^H^H^H^HBest Buy and Monster Cables.. I've actually been told that exact thing by a Best Buy salesperson. I, too, happen to know better, but I would say this still constitutes dishonesty on their part, regardless of my level of awareness. Unless there's a difference between 'telling the consumer an outright lie' and 'not telling them anything about a product (or at least hoping they don't ask) and assuming they know all about it already', this seems to turn the "simply selling Monster Cables for $50" or 'selling text plans for $5/month' or 'selling unhealthy $2.00 soft drinks in restaurants' into a bit grayer of an issue than suggested. (Quite a bit grayer in the area of soft drinks.. Whose responsibility is it to look out for a consumer's health: the vendor or the consumer himself? Restaurants sell alcoholic beverages as well, also at a tidy profit. Yet it's clear that alcohol impairs judgment and physical coordination even at low levels, which makes driving away from said restaurant an inherently dangerous undertaking. AFAIK, vendors of on- and off-sale alcoholic beverages have been successfully sued by the deceased's family for wrongful death caused by a driver impaired by the alcohol the vendor supplied. But this is now WAY off topic (not that it wasn't before...).)
That being said, I do agree that caveat emptor is a useful axiom to live by. I just wish it wasn't necessary to do so.