i don't consider myself an expert options trader by any means, and i haven't branched out to US options yet, i've just been restricting myself to trading ASX stock options for now. but my opinion is that MMs have access to a raft of info you and i probably don't, have sophisticated computer systems at their disposal, and on top of that are very savvy operators - if you try to catch them out purely on the basis of mispriced IVs, you are going to lose more often than not.
so i don't try to trade options on the basis of mispriced IV. instead i form views on particular stocks based on things i read, what i see in the charts etc., then i think about which options strategy/strategies would let me best trade that view. if i like what the market is quoting, i'll make the trade. if i don't, i'll hold fire and wait. i went into an example of a recent trade i did in a thread i started a while ago (
https://www.aussiestockforums.com/forums/showthread.php?t=26867).
i had formed an opinion on QBE, and decided that call calendars at 16 was the strategy i wanted to use. about a week before may expiry, the market gave me the opening i was looking for - the underlying got to 16, and with just a week to expiry some serious time decay would soon kick in, so it was a good time to put on the calendars with may being the near leg. the spreads were about 3c wide on both legs, which is probably as good as you're going to get in QBE for any contracts with a decent premium to them. i figured it was likely i'd be able to roll the near leg into june short calls (or june synthetic short calls - i didn't know which one it was going to be on expiry day - which is the topic of the above thread) at a good price because with a week to expiry, and the significance of the 16 level, there was a decent chance it would be near 16 at expiry, or soon after. adding all that up i decided it was good enough to make the trade, so went ahead and did it. whether the IVs were mispriced or not didn't factor into my thinking at all.
not saying that's the right way to do it, as i said i'm not an expert. so i'd also like to find out the approach other option traders take.
one other thing. i haven't looked at your spreadsheet yet, but i am in the software field, and can understand C#, so i might do at some point if i find the time. however from what you've said it sounds like you are looking for low IVs and high IVs in absolute IV terms, as opposed to
mispriced IV - which is an expression i generally take to mean that someone is suggesting that the IVs of the MM quotes are way off what they think the RV will be. which is why i wrote what i wrote in the first para. i might be wrong on the correct usage of the term though - i have seen it used before to describe lower strikes of the same underlying and expiry having a higher IV than that of the higher strikes and are therefore mispriced, when to me that is simply normal delta skew which you will see just about all the time anyway in stock options. maybe the term is amorphous and can mean many things. can you clarify what you meant?