The first question I have is a little more obvious, but I would like to have more in-depth explanations/resources for the second. These questions are based on an argument I had.
- Do advertisers give the products they advertise value?
My reasoning was that no, they do not give products more value. Useful labor gives value, whereas advertisements are both (a.) basically useless and (b.) not related to the production of the commodity. The person I was arguing with talked about how diamonds are useless, and they were artificially given demand by both ‘limited’ supply and vigorous advertisement campaigns. I replied that price gauging/differentiating exchange values does not mean an increase in use value/actual value, and the consumers were purely getting ripped off. The other person then said that advertisements, in fact, contributed to the inherent value of a product (somehow?) by making the consumer enjoy the commodity more. To me, even if advertisers were to produce use value, it would be in advertisements, not the commodities themselves.
- If (a.) an artist’s work is useful in creating art, (b.) art in society has value, and (c.) the value of art is ‘subjective’, do artists even produce use-value, or is art even subjective?
To address point number 1, the value that an item or commodity has is the product of its embodied labor, that is, the amount of work that has gone into creating it.
This, however, is separate from it's price on the market. They are related, and objects will usually sell for their valued price, on average, but that price also contains unpaid labor in the form of profit to the company.
What Marx points out is that this income from sales is separate from the costs that have gone into creating it. Creation was paid through prior income/capital, and this new revenue from sales will pay for the next round of production. This it is not guaranteed that the product produced will be sold, nor even sold for its value (if eg, the use value is low also).
So, advertising doesn't give value to the production of a commodity, but can open new channels to ensure that those products are sold and the capitalist can recoup money and profit. I guess you could consider that labor of producing advertising as part of the labor used to create the product.
So, maybe it does imbue the product with additional labor value.