I want to be a good lil' question answerer, so here goes:
"How did you determine the theme?" It was quite clear from the clues.
"If you did not get it from another source, how long did it take you to figure out?" Just two seconds, long enough to read the lengthiest clue. The clues to the themes almost always refer to "words marked with an asterisk" or to certain across answers (e.g., "12-across, 20-across and 33-across").
"And if you spent more than 20 seconds on it, was it worth the time?" Most themes are pretty obvious because of the clues. Sometimes a puzzle's theme answers will begin with similar words, such as BAIT, BEAT, BITE, BOAT and BOUT. Sometimes the theme answers will be homonyms or synonyms. In those cases, the theme will not be immediately obvious. But the time spent on recognizing the theme is only a few seconds...and I still have to fill in the answers. I don't even need to know the theme before I start entering words. My best answer to "Was it worth the time?" is: "Not applicable."