How to ID bad sap?

[Homespun]

I kept my taps in to hopefully get a little more sap from this week's short term cold temperature blast.
Any sap I collect will be kept separate from my earlier saved (in freezer) concentrated sap. I won't keep any slimey, ropey or cloudy sap.

What else should I also look for to ID "bad sap" that's not worth bothering with?
For example, is there a sap flavor or color I should look for that indicates bad or "buddy" sap when all else seems ok?

[adk1]

not that I know of. even cloudy sap isnt really bad sap. It will make darker syrup but may not make off flavored syrup.

[Michael Greer]

If it's warm, and the bucket smells like bread, the wild yeasts are active, and consuming sugar as fast as they can go. Cold slows them down, and boiling kills them.I have a number of customers that want dark syrup, and will wait 'til the end of the season to get it.

[DoubleBrookMaple]

I won't keep any slimey, ropey or cloudy sap.

What else should I also look for to ID "bad sap" that's not worth bothering with?
For example, is there a sap flavor or color I should look for that indicates bad or "buddy" sap when all else seems ok?

I have been researching this myself on this site, and in the UVM / Proctor Research Center library. First, do you really just want to to toss sap that is cloudy? I tossed some out of a bucket today that was really cloudy, but saving the less cloudy sap in my "bulk" tanks. The result will be a lower grade of syrup, and I want some lower grade. All my syrup so far is amber, and one batch of dark, but not grade B, or "very dark", and I want some with a strong flavor.
To answer your question, Bothering with is a personal judgement decision, based on your own needs.
Here is a very old UVM research bulletin #151 entitle "Buddy Sap" from 1910 that still applies I am sure. I suggest scanning through it, and you will know a lot more about "bad" sap. It covers "stringy", "green", "red", and "milky" sap.
I am still trying to find an association between tree buds, and "buddy sap". Everything I read in studies, only covers bacteria, or some other contamination as the direct cause of truely bad flavored syrup.
Here is some light reading for you.
http://cdi.uvm.edu/collections/getCollection.xql?rows=1&start=9&pid=maple (http://cdi.uvm.edu/collections/getCollection.xql?
rows=1&start=9&pid=maple)

[happy thoughts]

I am still trying to find an association between tree buds, and "buddy sap". Everything I read in studies, only covers bacteria, or some other contamination as the direct cause of truely bad flavored syrup.]

Here's a research article from 1950 I found at the Cornell Library. It associates buddy sap flavor with higher nitrogen levels in the sap. I haven't found anything yet at UVM though I'll bet it's in there somewhere if I can just define the right search terms. If you find anything else, please post it as I am also interested.

http://ecommons.library.cornell.edu/bitstream/1813/4305/1/bulletin742.pdf