My Blog currently uses the Fusion Theme from Digital Nature: http://digitalnature.ro/projects/fusion and the Thumbnail For Excerpts plugin.
In order to make an image show up without their custom treatment (the border, padding, etc), you will need to add custom styling to the image via the Advanced Settings.
- Click on the Image and click EDIT IMAGE
- Click the ADVANCED SETTINGS tab
- In the Advanced Image Settings–>Styles box, put this code:
margin: 0px; -moz-border-radius: 0px; border-radius: 0px; border: 0px; padding: 0px; - Update. Done.