I have seen many fish with ich, even the listed pseudos, blennies, dragonets, gobies, and triggers. However, like stated, they are usually less likely to get it over tangs, angels, etc. I don't thnk that means we should be listing them as "not prone to ich". The reason I said the following quote is so that the original poster does not get any wrong ideas about the fish he reads are "not prone to ich".
"Know about every fish you purchase before you purchase it and you will be much better off, I guarantee you."
If he were to go buy a mandarin now, that would be great because it might not be neccessarily prone to ich, but now he has a fish that is going to starve to death. If he were to go buy a SFE, that would be good too because they do not get ich either, however, now he has a fish that will get way too big for a 29 gallon (same with the trigger). Even though it may seem that some fish hardly ever get ich, if you were to let your water quality get bad enough with ich present, the fish are going to get ich. Also, if we were to list "blennies and gobies" under this umbrella of "not prone to ich", the original poster may think that all blennies and gobies are fine for his tank then. In this case, he may go out and buy a scooter blenny, or a lawn mower blenny, or an engineer goby, and not have the proper tank for the fish he purchased.
So boalgf, you were definitely right in saying that there are fish less prone to ich. I (erroneously) only said my original sentence in my first post so that the poster did not get any wrong ideas and just go out and buy a fish because it was less prone to ich.