Ethical advertising

This thread is inspired by the one about Lush, but I don't want to derail that thread, and this one is a lot broader.

Are you more likely to buy from (or bank with/take holidays with etc) a company with a good reputation for ethical standards, or are you cynical about claims that any company operating in a capitalist market is able to 'keep their hands clean'?

My take on it is that of course I would prefer to only deal with ethical companies (although, of course, not everyone's ideas of what is ethical are the same), but I can see that it is a high risk strategy for any company that has ambitions to move beyond being a local concern. Any claim that is later disproved can be far worse for a company's reputation than having no such claims in the first place, or even of simply stating that they are operating within the law, but selling as cheaply as possible. H&M, for instance, has been accused of 'greenwashing (ie pretending to be greener than they actually are). I am also dubious about brands that 'donate' something to a charity for every item you buy. You are buying at retail price, which includes their mark-up and on costs, and they donate at cost price, so make a profit on the donated item as well as using it to boost their reputation. In any case, I prefer to choose my own charities.

It can also be tricky to know which products are produced by which companies, as there are takeovers and mergers all the time (eg Jo Malone is now made by Estee Lauder, and the Body Shop by L'Oreal), as well as giant conglomerates who produce across a range of sectors (eg Nestle, or Proctor and Gamble) so a product or range that is in line with your principles one day can be at odds with them the next.

Banking is a whole other issue, as most fund managers will spread holdings over a range of sectors, and again, they can go from ethical to otherwise overnight if there is a merger or acquisition, and few people have the knowledge or inclination to keep a close eye on their pension funds or ISAs.

What about ecological/political slogans (eg There Is No Plan B, The United Colours of Benetton etc)? Do they persuade you to buy, or do you see them as manipulative marketing? Or stunts, such as Lush acting as a drop-off point for breast-binders for young girls, or M&S having bins to put old clothes to stop them going into landfill?

Do you take notice of this sort of PR, or do you just buy what you like if it's in budget, and ignore the rest?