What can disqualify an airport to be used as an alternate?
As far as Part 91 ops go, paragraph 91.169 is the only IFR alternate requirement to my knowledge.  

*Unless otherwise authorized by the Administrator, no person may include an alternate airport in an IFR flight plan unless appropriate weather reports or weather forecasts, or a combination of them, indicate that, at the estimated time of arrival at the alternate airport, the ceiling and visibility at that airport will be at or above the following weather minima:

(1) If an instrument approach procedure has been published in part 97 of this chapter, or a special instrument approach procedure has been issued by the Administrator to the operator, for that airport, the following minima:

(i) For aircraft other than helicopters: The alternate airport minima specified in that procedure, or if none are specified the following standard approach minima:

(A) For a precision approach procedure. Ceiling 600 feet and visibility 2 statute miles.

(B) For a nonprecision approach procedure. Ceiling 800 feet and visibility 2 statute miles.

(ii) For helicopters: Ceiling 200 feet above the minimum for the approach to be flown, and visibility at least 1 statute mile but never less than the minimum visibility for the approach to be flown, and

(2) If no instrument approach procedure has been published in part 97 of this chapter and no special instrument approach procedure has been issued by the Administrator to the operator, for the alternate airport, the ceiling and visibility minima are those allowing descent from the MEA, approach, and landing under basic VFR.*

**If you look in the front of the approach book (DOD or JEPP) it will list the 600/800' limitation for alternate designation.  I guess it's not in the UPT syllabus because the 11-214 (and the DOD for that matter) doesn't honor that specific alternate limitation.  FAR Part 135/121 ops might list other limitations that look like the "RVSM reqd, Wx reporting, GPS only, etc.)

-the queep monster....**