Sounds like pilot's good judgement is called for those marginal cases.
Keeping in mind also that not everywhere you can get such detailed information to make the "right" (or the lawyer's) choice...
I was taught to always go to the safe side instead of having little chances or (margins) to err. Especially when it comes to runways; so I'd take "contaminated" figures please.
Asking the ATC for the runway status, also other landed aircraft and some dispatcher on the ops frequency seems a good deal for me. Adding that to what you can see through the windshield (if that's somehow possible...), the METAR and/or a TAF seems about enough to make an educated decision.
You might also land a bit before the aiming points if conditions permit, that way you can get some extra feet just in case. Although I reckon that if you need those extra feet, probably there's something wrong with your numbers
There's always the possibility of a missed approach if you count one too many centre lights passing by...