Based on my own experience trading DITM illiquid simple options, when I sold, mostly I was selling intrinsic value with little premium, but when I bought, I had to pay premium. In other words, mid points were not representative.I think it's because the spread is so deep ITM, that's why the spread is huge.
I only trade spread when I have to leg into it and I usually leg out so I have no experience trading spread as a unit.
