Pasting content directly from Microsoft Word can create serious formatting problems, but there is a trick to avoid it.
When pasting from MS Word, click the  button at the end of the editor toolbar in WordPress to open out the second row of the toolbar.
Then click the "Paste from Word" button  on the second row which gives you a pop-up to paste the content into.
This pastes it in without all the MS Word codes.
Most alternate text editors in WordPress, as well as those in Joomla, seem to have an equivalent "Paste from Word" button.