Exactly. You need to add conditions, like, "for a PS3 game" or "for a new IP."
You can't say "LBP was a huge success saleswise" and not add a condition, or you'd be purposefully misleading whoever you were trying to convince.
We have to judge these things relatively.
Sure, even without conditions, LBP is a success, you could call it that. However, leaving out any conditions would be purposefully remiss and non-descript.
I could easily say that "Ninja Gaiden 2 is a fantastic game." However, that's not really telling the whole story is it? It's not really a lie, and it is certainly my opinion, but I feel I would be being a bit biased if I told that to a n00b.
Same thing with LBP having "amazing success in the sales arena."
Then Mario Kart Wii is setting in the bar, and wtf. I get busted out as a liar.
The hype train praise LBP as a fantastic game, a pioneer of innovation in gaming and at the same time a link to video game's forgotten pass. Most media agree, praising it for delivering everything it had promise and more, although personally it was not to my taste (I still bought it).
With regards to the sale however, most of the sensible crowd had predicted 3mil+ life time sale which was an achievable and very sensible estimate, especially when it was widely known well before the launch that the game would be heavily bundled.