Inspecting frames for damage

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Slight(or worse) ripples along the top tube and downtube near head tube indicate head on collision.
Rear drop-out spacing, check for compression.

Good advice - also:
Check seatpost is free and snug and has decent insertion.
Look down along the length of the seatstays for visual evidence of damage to them.
Fit some wheels and check they are aligned vertically by sighting from the rear of the frame a little distance back.
Also check clearances on down tube for evidence of frontal impact, and fork crown / chainstays / seatstays for symmetry.

Another thing; do you guys have rules of thumb to tell at a glance how 'tracky' a second hand frame is? I personally find it a bit tricky when I see frames without wheels on photos or when I see some half disintegrated thing at a jumble sale.

In order to have the best crank clearance possible the angle between the head tube and chainstays should be as large as possible right? What about the fork angle/position? Large angle of seatstays and chainstays angle means tight rearwheel? Perhaps not? Headtube lenght? Angle of seat tube relative to what exactly? Other things?