I don't know which fault where Explorer and Opus show icons correctly for Dropbox folders.
But incorrectly for SkyDrive.
It is Opus or Microsoft fault?
Opus just asks Windows for the icon and overlay information, unless configured to show generic icons for the type of drive (in which case neither would work), so i don't know why SkyDrive's icons wouldn't be working unless SkyDrive intentionally avoids adding the overlays outside of Explorer (which some shell extensions choose to do).
Do other people using SkyDrive see the same thing in Opus and Explorer?