You're right, the VX did not come w/ the door protector, but it could have been added afterwards.
A couple of ways to determine if it's a real VX:
1) The oil filler cap is in the correct upper right part of the valve cover (DX is on lower left corner)
2) Transmission code on transmission housing to the left of the catalytic converter should be "J8B" (or at least begin with the letter J).
3) Engine code stamped on the engine (also to the left of the catlaytic converter, right next to the transmission code) should be "D15Z1"
4) The VX has the EGR parts on the firewall behind the intake manifold.
5) Go to this online Honda dealer parts website: http://www.bernardiparts.com/SearchOptions.aspx
and type in the vehicle's VIN # in Option 1 field and select "Enter". The Search Criteria field will show the exact model car. This will only tell you what the car was originally, and not what engine and tranny are in it now (if it has been molested over the years). My second, third and fourth suggestions will determine if it has a VX engine and tranny.
My VX info thread
It's the first clickable link in that thread, shows how to tell by VIN
I can see by that engine bay picture that it has the EGR box on the firewall and the spark plugs are in the proper place. I can't see the VTEC solenoid, but check the engine stamp for "D15Z1" and you can tell for sure that the motor has not been swaped out.