One thing that formula companies do that I think is unethical is give major rebates to WIC (in the area of 95% for each can, making a $20 can of formula cost WIC just $1), which results in higher prices of formula for everyone else (the freebies do this too, but I think to a lesser extent since there is way more WIC formula than free givaway formula). While it does state in bid documents that the cost of formula mustn't be inflated because of the rebates, there isn't really a way to police this and make sure that doesn't happen. Considering about half of the formula fed babies in the US are on WIC, the bulk of the formula industry's profits are from those who pay full price for formula. Also, because so much of WIC's funding is dependent on formula rebates, in many offices WIC will seem to push formula much more than breastfeeding (though it is not true in all offices).
Here's the link for one of the WIC contracts. Whenever this subject came up in the past I would never directly link to it because I was employed by the state agency that produced that contract, but I quit my job in May so I'm not worried about getting in trouble anymore! It is public information after all.