Plugged a Bluetooth USB to Tablet but seems not working I have insert a USB Bluetooth dongle to a Tablet via the USB port and try to turn on the Bluetooth in the Android but fail.

So, how do one know if the USB Bluetooth dongle can be supported for a tablet that have a USB port? (Given that the USB Bluetooth dongle have been tested to work fine in a desktop PC and there is no further information on the tablet manual on which Bluetooth dongle is supported for the tablet.)

The Ice-cream tablet was not rooted yet.

Is there some kind of Android Apps that can check or verify the above scenario?
Most tablets that comes with the Bluetooth share app installed, and have a Bluetooth option in Settings, while not having a built-in bluetooth, typically indicates support for such dongles.

I have used generic Android TV Box (CDR-King brand) with no bluetooth built-in but has a menu for it. Plugging a bluetooth dongle to a usb port activated it. Based on this, your tablet's ROM does not support bluetooth. My advice is to root it, and flash a custom ROM with bluetooth support if applicable.