Bluetooth on Linux VM hosted on Windows?

but if I cannot capture Bluetooth traffic using Wireshark on a Windows laptop, I'm probably not going to be terribly successful capturing Bluetooth traffic using Wireshark on a Linux VM hosted on that same Windows laptop, am I?

You might be.

If the virtual machine software provides a Bluetooth interface on the VM guest machine, using the host machine's Bluetooth adapter, and if the Linux recognizes that Bluetooth interface, you should be able to capture Bluetooth traffic between the Linux guest and other machines. However, you won't be able to capture Bluetooth traffic between the Windows host and other machines, and you won't be able to capture other Bluetooth traffic - traffic between two other machines - on the Linux guest.

If you want to passively capture third-party Bluetooth traffic, between two other machines, you'll need something such as Ubertooth software and a device that supports it, such as an Ubertooth One. Ubertooth might work on OS X, but doesn't appear to work on Windows, so you'll have to run it on your Linux guest, which will require that the virtual machine support connecting to the guest USB devices plugged into the host.