Mr. T. I suspect your ports were originally anodized or painted. The coating has broken down for some reason. The white powder is aluminum oxide formed when water/water vapor comes in contact with the "raw" Al. NO idea why this should occur in only one stateroom but perhaps, "steamy" undertakings...enough said.
In any case, short of removing the offending ports and either replacing or re-coating, what you might try is cleaning them off really well with a good detergent agitated with a toothbrush followed by a wipe down with, say, acetone or denatured alcohol and giving them a couple of coats of clear sealer with a small brush. This is NOT a permanent fix but may minimize further "dusting" of oxides.