There is also a difference between bidbots (as they currently work) and advertising. When you pay for an advertisement, you have no guaranteed return, no-one is obligated to buy your product. There is an element of risk. Bidbots should also have no guaranteed return. However, if we refuse to downvote them, then we are basically allowing them to force us, as a community, to purchase their content (via the reward pool).

It is precisely the lack of risk inherent in them that means they are scamming everyone else. This is why I do not see a problem in them being downvoted. Introducing that element of risk will make people more cautious in using them, especially for low quality content.