Invisible characters causing line breaks in posts

I have a client who blogs frequently. We have started seeing odd line breaks and word spacing in her posts. I found the problem by pasting the raw test from my client’s blog posts into my text editor (Coda 2), and checking the Show Invisible Characters option.

I discovered that she has two kinds of white spaces in her text. The common space is represented by a dot at the baseline of the text. The other kind is represented by a tiny ^ mark (but much smaller) that is positioned well below the baseline of the text. If I manually delete these marks and replace them with normal spaces, the text looks much cleaner on the blog.

Does anyone know what such characters are called, and how they might be getting into a text file? My client assures me she is not using MS Word.

Ideally, I’d like some sort of filter that strips and replaces these odd spaces with normal spaces.