I find it interesting that 19 folks say it's OK to dip coins as long as it's done right, but not a single person admitted to having dipped coins in their own personal collection.
I dipped an NGC MS64 1921 Peace Dollar and got it in a PCGS MS65 one. It needed to be lightened to help preserve it so it didn't go black. Luster up the wazoo and hair!
Welp, @baseball21 would probably either dispute what you write here, or at least have a coronary event. NGC64 becomes PCGS65???? I have ZERO surprise at that, but "base" is going to have a problem. (as may more than a few PCGS-snob dealers)
I took an 1846 Seated $1 out of a PCGS AU Details Environmental Damage holder (90% of the obverse was covered in a thick layer of black crud but luster was evident on the remaining 10% and the reverse) and dipped it. It is now on its way back from NGC in an AU55 holder.
I picked only if it's done right. I don't know how to dip a coin, so I just don't do it. Now if the question is, do I have dipped coins in TPG holders that are straight graded? Then my answer would be yes. But they did it properly.
It was an exceptional coin. I have posted the picture of it. I diluted the jewelluster and only did spot lightening. I cracked it from its NGC MS64 tomb and sent it to PCGS where it came back MS64. The dealer that submitted it told me that if I did it a couple of more times I would get it in a 65 holder. I got lucky and got it in on the 2nd try. It has full hair like a Dan Carr piece.