I am not very surprised with the fact that semantics is not just about language or linguistics; it is also about politics, marketing and finally... money!
To give you some key examples in the groceries field (although this is very general), those products that are made with "natural and artificial flavors"... it is quite clear to me what is an artificial flavor; I haven't been able to evaluate what exactly means a natural flavor. You see, you could argue that they are natural because they are made with natural products, but then the raw material to make an artificial product was taken from the "natural word"! so it seems that artificial means that the actual flavor is quite far away from the original raw material while "natural" is closer to the raw material, few processing going on.... so the semantics? in my dictionary a natural flavor comes from natural flavors, no process ought to be involved!!! thus the definition is twitched quite a bit to label the cans of products that you would buy in a supermarket; i.e. from a hard semantic point of view there is not such a thing as a natural product.
Another interesting example is found in some products that are sold in California, in which there are some chemical or something that probably is (very!) harmful for human beings. You will notice that those products would have a label that begins with a sentence more or less like this: "It is know by the state of California that this product can produce cancer" ... what does it means this? that the people in NY don't know or the people in NY pretend that does not know? here is a beautiful example of how politics change the meaning of words; in California the product is not acceptable because could produce cancer, but in some other state, this is perhaps known but not legally addressed... it wouln't be ok accept something that is not accepted in a different state unless, of course, the subject is not known! so California knows something that some other states don't know! better to be dumb and blind than an inmoral seller!
Finally, my favorite one, a "Guacamole style" sauce that does not contains avocado, the meaning of the word "style" would be "fake" but at least with "style"!