Invalid characters in XML feed data

I have a feed that I pull data into a database from. It provides the data in XML format. However, the data includes "illegal" characters. For example:

A GREAT NEIGHBOURHOOD – WITH A

or

large “country style†eat-in

or

Garage 14’x32’, large

or

 OR…….ENDLESS POSSIBILITIES!! 

My question is first, how do I identify the encoding of these characters, and second, how do I change the encoding to match the UTF8 format expected by my database?

EDIT: To be clear, there's no database involved in this process (at this point in the process, anyway). The data will be inserted into the DB later, but at the moment I'm just reading the data via a PHP script and printing it on screen using var_dump.

EDIT 2: the data is being pulled from a RETS feed using the PHP PHRETS library