Well....Just returned from cruise on spirit.....and if it covers your body is is in the dress code.....saw lots of people with jeans, all kinds and all conditions....and well the tops were everything from collared shirts to ones that were advertizing anything...ie... corona, anything goes....very , very casual
We noticed that on our last NCL cruise also...and even on our last RCL cruise...Jeans were let in on Formal night...guess jeans are formal wear to some....but each to their own...I will dress nicely and don't care what the other guy is wearing....we all paid our money....Happy Sailing...