The Time Lords of Gallifrey have a particular interest, as Gallifreyans ferment certain types of sugar internally as part of their ordinary metabolic processes.
In short, whereas a human being may only get a sugar rush and quick crash from candy floss, the substance has a similar effect to alcohol intoxication on the brain of a Time Lord or Time Lady.
Studies continue, but the intoxicating effect appears to be a reaction between candy floss and ingesting the Elixir of Life as provided by the Sisterhood of Karn. If the subject has regenerated frequently, it has been known that larger amounts of Elixir will be collected in various organs, which only intensifies the effect - especially if one or more incarnations has been triggered through artificial means. Gallifreyans who are not Time Lords and therefore have not regenerated or travelled through time, appear to only gain a short period of mild intoxication, which appears to support the hypothesis that Karn’s Elixir of Life is required in conjunction with candy floss for severe intoxication. Time Lords enjoying candy floss have reported that at times they can “see scents or sounds” and have the ability to break free from time loops at will.
There are of course, unpleasant side effects to candy floss intoxication, as Time Lords discovered under the influence inside the Citadel have known to be arrested by the Chancellery Guard*. Also, Time Lords in this state are advised not to operate Time Travel Capsules or other multi-dimensional machinery, and to avoid danger, as excess amounts of candy floss in the bloodstream may inhibit a Time Lord’s ability to regenerate.
*footnote: One famous case is of course Theta Sigma (aka the Doctor) vs. Borusa, which ended in academic disciplinary action and the invention of the bootstrap paradox.