I’ve been helping a friend setup a new forum using Simple Machines Forum (SMF) and even though it worked fine on a previous installation I’d done, the pound signs (UK currency, not a #) just wouldn’t show up as anything but a ? once they were posted.

The forum was installed onto some webspace provided by Daily Internet rather than on my own server so I had plenty of things that could have been different.
At first I thought that there was something different about the PHP settings and a default language or encoding, but the only things I could see were the same. Next I thought perhaps the MySQL database had a different encoding default but all the tables were set to latin1.
I was getting ready to try converting the whole database to utf8 and adding the SMF language packs for English-UTF8 when I spotted something in Settings.php
Right at the very bottom, just before the closing PHP tag it said:
$db_character_set = ‘utf8’;
Now given that all the other encodings said latin1, I thought perhaps that might be the cause.. and I was right. Changed it to latin1 and pound signs and accented characters could be included in postings.