Using date_ical, I fed some fields into the description of an ical. The output had an ascii  inserted between field label and field value. After debugging I found that it was in the place of any space HTML entity " " that was found in the data fed from date_ical to drupal_html_to_text.
The call went drupal_html_to_text->filter_xss->_filter_htmlcorrector->filter_dom_load->(core php)DOMDocument()->loadHTML. Now this appears to be an encoding issue as other PHP applications have seen similar behavior but I can't determine if the issue is with DOMDocument() or with how it is being called by filter_dom_load().
To fix this I wrote a module that replaces all " " html entities with an actual space. Reporting this in case it is in need of a real fix. I did try to hard-set the encoding type to "utf-8" via DOMDocument()->encoding but that didn't help.
Thanks.