adds can be done well if they're not intrusive, adds in games with real life settings are ok, as it brings a sense of realism into the game, but at the same time advertising their product, and of course the revenue generated should go to maintain game servers and or at least some extra cheap to free DLC.
The wrong way of doing in game adds are those that are intrusive, such as showing up just before the game loads, it makes loading times longer and brakes the fluidity, although if their are adds in the actual load screen and load times are not affected then it's not to bad, again the revenue must be used for something that will to some degree benifit the end user.
The worst way of advertising in games would be to have adds show up in games whose settings are not based in reality. so any CELL shaded, Sci-fi, or medievil game settings would be a no go for in game adds as they will break everything.









