i love the ao feature in the gi settings and use it at a low level on almost every job.. not physically correct but adds solidity to everything.. especially when using imap.
however there are cases when i dont want it on specific objects.. carpets for instance tend to get pretty heavy looking with ao on. be nice if there was a include /exclude for this feature. save me having to comp it after.
extra tex with dirt map could do the trick, just paint the AO where you need it in PS. you can have them as many as you want with different AO for flexibility.
yeah that is my general method in this case.. just thought an extra control in vray might be nice. 
I may be missing the point here, but why not use the exclude feature in the VRayDirt map?
Edit: grammar police. 
just cos that means i have to put a vray dirtmap in every material in the scene to achieve the same effect as the simple checkbox in the gi rollout.
There is no need to add Vray DirtMap to every material - like urbanite mentioned earlier Extra Texture Render Element with Assigned DirtMap could be used then you can exclude element either from ExtraTex option or through VrayDirt options.
I’ll make a note about adding this possibility into GI-AO as well.
Svetlozar,
Is it possible to have the objects excluded from the vraydirt be another colour than black? Maybe the unoccluded colour?
I usually exclude trees from dirt passes in exterior renders but I have to add a multimatte to mask out the black trees in the extratex so they dont affect the trees in the base render.
If you need a sample of what I am talking about I can set something up for you
Unfortunately it is not possible to set a custom color of excluded objects because they are excluded from the rendering.
What you could do in this case is just to invert occluded and unoccluded colors - usually for AO white is used as onoccluded color and black is used for occluded, however if you swap those colors you will have the negative result - but at later stage if you invert this image in compositing software all excluded objects and background will be 100% white and they won’t affect the end result.
That is actually a good idea!
Thanks for the suggestion
+1 in this.
