I know this is probably not what the OP wants to hear but you just have to get a feel for this on your own. Once you begin to focus on nutritional values with foods you can identify completely, you'll get a better sense of how to apply that knowledge to foods that are more 'mysterious.'
A couple of things to remember: in many cases, restaurant portions are much larger than a typically-recommended portion. Also, processed foods generally contain a lot of sodium; far more than you might expect. Generally speaking, if something tastes better than the sum of its parts likely should, there's probably a good reason for that. It is difficult to eat nutritionally well and inexpensively in most restaurants. Ironically, the biggest chains are the ones that are most likely to provide nutritional data for their menu but those are generally the hardest places to eat in a nutritionally balanced way. At smaller, individually-owned places, you may not always be able to eat properly but in most instances, those are the places at which you're likely to get questions about what's in the food answered.
=R=
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