tomorrow i got an appointment to go to a regularly closed to the public junkyard/recycling plant prior to opening for the hour, and from what i hear has collected a ton of bikes mostly vintage and classics. What are some good guidelines for picking bikes? what should be the brand food chain i go by? what parts should i look for and what in general?

sorry, i'm kinda new to vintage bikes (no sense of value bought a working hi-ten nishiki rally for 75 bucks got ripped ) and this is going to be a very rare occasion so i want to know whats good and whats not worth the time.

It's kind of difficult to convey years of knowledge on hundreds of brands and decades of technology and culture in one night.
Any chance you could take someone with you that knows what they're doing and has a good eye?

Not really because its kinda under the table thing, but theres no websites out there that sum up some key points? well besides sheldon brown?

Frankly, no.
Better quality frames will be lighter than others and have smooth-looking brazing around the lugs - which will be a nice shape with good proportions. Pantographing (stamping or machining the manufacturer's name into components) was common on older high-end bikes. Campagnolo is a well-repected brand that is valued pretty highly. These are some generalizations.
This junkyard/recycling plant wouldn't be a stolen bike dealer, would they?

For what you are looking for, this thread would be a good place to start:

https://www.bikeforums.net/showthread...e-Flipping-101

thats what i'm looking for no its a local recycling/ junkyard my friend works at and they just got the left overs of a ton of older bikes, but i can always check the serial to see if they're stolen :3