Most robots will read OL (over load or immeasurably high resistance). This should be your ideal target, and I'd insist on it before bag'n'tag. If you are measuring hundreds of kOhms at a regional, you likely have more important things to do. In any case, keep an eye on it and re-measure every time you do something that might risk a short.
OL: You are done! Measure again before your next match.
0-10 Ohms: There is a direct short somewhere in your system. You are likely to light on fire the next time you get rammed.
90-110 kOhms: One of the devices you have pulled a breaker for has a short close to its positive lead.
1MOhm + : You might have a short down stream of a piece of silicon. The actual value read will heavily depend on the exact model multimeter you are using. This is often also polarity sensitive.
Here are a few that I've measured with my multimeter, YMMV:
Grey Jag Power Output:
2M Ohms to PD + or -. Takes 15 seconds to stabilize, invariant with meter polarity.
4 slot cRIO chassis:
10kOhm to PD - with positive meter on PD.
9kOhm to PD + with positive meter on PD.
Oscillation with negative meter on PD.
Could others add to this list?