More or less deceiving visitors is not ennobled because everybody else does it.
Later when they got ads and "sponsored results", which they had to do of course because at some point you've got to make money somehow, they were very very careful to distance their ads from search results, because after all they'd just been promoting themselves as "not selling their search results" and of course "Don't be Evil" (which they dropped by now right).
And ever since, their ads have been creeping closer and more visually similar to their search results, right up to the point where, as the OP mentions, some of these ads look exactly like search results, except highlighted. Sure they are marked as "sponsored result" in very tiny light-grey letters but so were some of their search-result selling competitors back in the day.
So yeah no sorry, I fully understand this is the way corporations inevitably go as they get big and successful, but as far as I see it, Google has been distancing itself from this "evil" behaviour at first, and then, after competition was crippled, slowly crept back to--well not the worst examples of this behaviour, but it's still bad enough that if Google had been selling "sponsored search results" in this fashion right from the start, nobody would have bought their bullshit about "we don't sell our search results".
What they're currently doing is only marginally better than silently hiding sponsored links within the search results, as from every approach they're going through lengths to make this ad look exactly like a search result, except they highlight it and tiny letters say it's an ad (the 8px kind that UX blogs will tell you a lot of people have trouble reading).
I even just noticed they gave their "top search result ad" exactly the same ">> Preview" button on mouseover as any other search result! Sorry but there's no question that what Google is technically doing right now, is selling their top number 1 highlighted "search result", misleading people to look exactly like a search result, except in a token-attempt at "honesty" it is marked as an ad, except you know as well as I do that the less computer-savvy people don't even notice that, and just click it if it seems to answer their question, without realizing it is an ad. Just as if it was a search result.
I mean, hey I think it's bullshit, sure they're allowed to do this, but let's not pretend Google is not selling (top) placement in their search results, and that this top ad is not desperately trying to look and behave exactly like a search result in a deliberately misleading way. They are no longer any better than the competitors whose ad model they were so against back in their early days.