How long does fresh orang juice last?
Fresh in the sense of fresh squeezed, not pasteurized, right? We just had a similar thread with the OP wanting to squeeze quite a lot of OJ in advance rather than every morning. The resounding response was every morning and finish it by afternoon, if not sooner.
The faster you finish it, the fresher it'll be. Sure, it'll most likely last a week, but it's a fresh product and will deteriorate fairly quickly, nutrient-wise.
On the downside, It may ferment rather quickly, although you'll probably finish it first. Fermentation is related to the ascorbic acid concentration levels in your juice, if it's low, then it'll go. So you could have fuzzy OJ inside of a week.
I think, and I could be wrong but this is my hunch, that if it were bad you'd be able to tell right away. That's the beautiful thing about produce; if it goes bad it doesn't try and hide it.
If it has gone bad, and you have a sip, I don't think it would really hurt you either. Whenever I've made fresh juice of any kind, I just keep drinking it until it tastes bad. I've never had a problem.