Distinguishing between a weakly brewed bad cooked pu'er and a weakly brewed bad oolong can be more challenging, especially if it's teabag tea. I had this problem the other day - I couldn't tell what kind of tea the restaurant was serving me, other than that it was absolutely awful. In some cases, it may even be a mix of two or more types.
To the OP: Chinese restaurant tea really varies, depending on the location of the restaurant, its main clientele, the region the owners are from, and the type of food served. Here in the SGV area of Los Angeles County, one of the biggest ethnic enclaves of Chinese food in the US, and arguably home of some of the most authentic regional Chinese food in North America, almost all restaurants serve teabag Jasmine tea (or, less commonly, teabag oolong or pu'er). And yes, they serve the same junk to ethnic Chinese customers as to white people, typically. If you're lucky, you might get a choice of teas, or something slightly better (bad quality cooked pu'er, green-ish Tieguanyin oolong, or a better grade of looseleaf jasmine) at dim sum places / Cantonese banquet places.
If you can tell us what the leaves look like (assuming it's looseleaf tea), or better, show us a picture, that might help. Honestly, though, most Chinese restaurant tea is pretty bad stuff; if you're looking for stuff to drink on its own (not to accompany food), you might try to find some slightly better tea that has some of the same characteristics you find enjoyable about whatever tea it is you're drinking. I.e., if it's earthy and dark, try cooked pu'er. If it's roasty and fairly dark, but not that flowery, and with maybe a bit of a raisin-y taste, you could try darker roasted oolongs. If it's really floral (in a scented, jasmine kind of way, not in a natural way), try Jasmine tea. I would think that part of the secret of getting that kind of bland, unoffensive taste that restaurant tea often has is simply to brew it with a small amount of leaf, and let it sit for a while.
I have seen bags of "Chinese Restaurant Tea" (maybe Foojoy brand or something like that) at some markets and stores, usually in 5 lb bags. Dynasty also makes a "Chinese Restaurant Tea" teabag tea, which they claim to be a mixture of jasmine, oolong, and green tea (sounds awful); this is available in smaller boxes.
I know there was a really godo thread about this somewhere, but I can't seem to find it. I did, however, find a few threads that might be of interest:
http://www.teachat.com/viewtopic.php?t=7314
http://chowhound.chow.com/topics/349556
http://groups.google.com/group/rec.food ... n&ie=UTF-8