Leafing through various monster books, one will note that often enough an entire race or species of creatures will be described as being of Evil Alignment. This is something that irks me somewhat, though I can see that it might simplify matters for some people; after all, if all kobolds are innately Evil (with a capital E) then for somebody like a paladin, slaughtering them indiscriminately is not only OK, but a positive duty.
For me though, I think it's just Lame. With a capital L.
I prefer not to go with species-based Alignments, because I feel that it dilutes the concept of Alignment as a character-driver. Alignment (in my campaigns) is pretty much always a choice, unless you're playing a class like Paladin that has a specific Good Alignment restriction, or encountering outsider-creatures like demons, or undead, which are innately Evil (and in the case of demons and what not, probably also pretty evil).
In other words, for the purposes of detection, I make a distinction between Evil and evil, and between Good and good.
Having said that, in races/species like orcs there will likely be a higher proportion of Evil individuals than in some other races, due to there being more initiates of Evil cults and so forth.
Also, I'm not enamoured of the idea of evil/good detection acting like a pair of "Evil-Vision™" goggles. I prefer to run it as a fairly non-specific emotional awareness, with maybe a rough indication of direction if it's someone or something actively Evil (i.e. "there is Evil here.... " rather than "the third button down on that guy's waistcoat is an Evil button...")
If players in my campaigns want to go slaughtering infants, well that's fine I guess, if that's what floats their boat, even though I personally find it rather despicable. But I want them to make a moral choice to engage in that sort of behaviour, and not just leap at it because the Rules Say It's OK.
Just because you're Good, it doesn't mean that what you're doing isn't evil.
Postscript: I've noticed a few people on one of the message boards I frequent saying, on this subject, that they like having black and white racial stereotyping in their games because they don't want to bring "modern morality" into them. Several people said they preferred it because they play to "escape from real life". I may be generalizing here, but it sounds to me like the sub-text is "I want to act like a complete arsehole, but I can't get away with it in real life, so I want to be able to play-act it at least".
Of course, that's just my opinion.