One of today's theme answers can also describe the theme entries: ODDDUCKS, which, according to the revealer at 66A are "Certain spears ... or a curious spelling feature of 1-, 20-, 26-, 45-, and 53-Across?" (TRIDENTS). I get the spear part, but was a bit perplexed when trying to figure out how it applied to theme answers, in each of which one letter appears three times in a row. It crossed my mind that all the repeated letters could be "dentals" in the phonetic alphabet sense, but I don't think vowels (FREEEMAIL) are ever dentals, so, that's probably not it. Anyone? My personal confusion not withstanding, I liked the super weird looking triumvirates. The aforementioned ODDDUCKS is my favorite, but I also like SUEANNNIVENS and DRESSSIZE.
The grid includes some possible themish also rans - additional fill with double or repeated letters - like NOOGIE, ALANALDA, LATTEART, and ANDEAN.
Imagine with what elan I espied 33D: Jai __ (ALAI)! When was the last time we saw that old chestnut? (September 10, 2017 - thanks XWord Info!)
Are there clues that could use a DUOver? Sure, maybe a few, like COL, SYST, PSAS, IAM, MSN, and SHUNT (I really don't like that word!) but any puzzle that includes PALMEDOR, DRAB, ZEST, SAUNA, and SONATINA BINGES along with those wacky triple-letter theme answers is okay with MESAS.