A number of folks have reported issues from scented candles.
In general, any significant delivery of organics to the aquarium has the potential to drive bacterial growth, although rarely is it anything more than an aesthetic problem.
Do you use a skimmer and is it sucking kitchen air? Do you use the vent when cooking things that splatter oil and such?
Thank you for addressing my concern. My temporary tank, a 40B, is set up in the kitchen about 20 ft from the cook top. We do use an exhaust fan. Interestingly, I am having issues. Started with cloudy water. A very expensive and nice candle was burned recently in the kitchen. hmm? I am not currently using a skimmer. Just a HOB large filter, and a powerhead. I never really noted problems before with scented candles, but my DT is a much larger, enclosed, and much further away from the cook top, and the area where the kids burn candles. This is something I will have to pay close attention to over the winter. Thank you.