I fairly recently spent a night with a guy who I strooonnnngly suspect has thrush (and who gave it to me, hooray), and I didn’t notice when I kissed him, but it was noticeable the next morning. Like, morning-thrush-breath is a thing, I think. When I got thrush from him, I noticed it on myself a little bit first thing in the morning. Fortunately, mine has pretty much subsided (a month later), but I was otherwise symptom-free when I got it.
It’s also probably responsible to keep in mind that you can pass thrush along to someone with whom you’re in intimate contact. I don’t think that would cause someone to have a system-wide candida overgrowth, but it doesn’t help. I got laryngitis from that guy mentioned above when I got thrush from him. A win all around :p