Given the text:
"I don’t expect these companies are pouring money into R&D to design the latest bags; market research isn’t that expensive and because it’s fashion, what ever they say the latest fashion is - then that’s what it is."
The preview and the published page write R&<smiley>. I have to write "R & D" in order for it to spot that there is an ampersand. If I write "R&D" it still gets it wrong.
It looks like there is a precedence issue where the thing that spots smilies runs before the thing that converts ampersand codes into characters.
Just disable smilies for this particular post, there's a checkbox for it.
This is not a bug but rather a normal behavior everyone would expect with enabled smilies.