If you compose your ad in a text editor you may be picking up some invisible formatting characters which will appear when you paste into our form.

Try saving/exporting your document as a plain text (.txt) file and copy your content from this file.
This should strip out any markup that your text editor adds.

You can also login and manually edit out these characters after an ad is approved, but it will have to be re-approved.

Sometimes we edit out these characters for you when we have the time.