When you remove formatting from text in Atto, it wraps the selection in a meaningless span tag with no class or id, leaving some messy HTML.
- Create some text in an Atto editor
- Highlight a phrase and select Bold
- Unselect Bold
- Examine html with the Show HTML button
The text now includes various span tags littering the HTML
Tested in Chrome 35.0.1916.114 on Mac and Safari 5.1.10 on Mac