The HTML Decimal (the # code) characters in that post are HTML but the post is being saved as BBCode only.
It looks to me as though whatever program your user who created the post is copying and pasting from, is also copying the HTML text in to their post. As a guess, an easy solution would be to just have the user not copy from Microsoft Word (or other graphical word processing program). The HTML Decimal (the # code) that is being used is a "Letter Turned Comma" rather than just the regular apostrophe.
Further on that guess, it looks like it could have been typed up in a WordPress editor, then copied through the users browser "copy/paste as raw html". I'm still not sure about that.
But i am sure that is HTML attempting to be posted to a BBCode ONLY entry box.Upon further inspection, it just looks like the user is attempting to use a "Letter Turned Comma" instead of an Apostrophe in their post. This could be due to copy/pasting from their third-part text editor program (which they initially used for typing up the post) trying to be helpful by visually inserting a character that looks correct -- or by the user incorrectly using the HTML Decimal symbol key on their keyboard that looks similar to an apostrophe, but is not an apostrophe.
Example:
![[Linked Image]](https://www.ubbcentral.com/forums/ubbthreads.php/ubb/download/Number/2031/filename/20160330-apostrphe.png)
Further reading at:
http://www.unicodemap.org/details/0x02BB/index.html
