Smile but say nothing. Saying something, such as quoted in the OP, is another way of saying "you don't pass".
If you MUST say anything, leave out any reference to CD, TG, TS. Instead, something like "very pretty" or "nice dress" will do.
Imagine a stranger saying to you "wow, you pass so well". Wait a sec, if I pass so well, how did you know........"
Duh.
