Hoarding SD adverts all over SJP may p*ss a lot of people off, but -- again, from a purely economic standpoint -- it's a fairly zero-sum trade-off for him. While SD gets 'free' advertising which is worth a couple of millions, the club he owns gives up the same value in commercial revenues which it would get if it put up paid ads on those places. Given that he's not reinvesting a penny the club makes, it wouldn't really make a difference if another company would pay for advertising in SJP and SD would spend the same amount of ad money elsewhere. He could just take that money out of the club. That would still p*ss a lot of people off, although probably not as many and not as much as the SD adverts.
Makes a big difference when we are told we cant compete with Norwich, Southampton, Everton Swansea and whoever else is outside that top, when that commercial revenue could potentially give us the edge...it has in the past.