Uhhhhh.... Well... I don't know that I'd ever brush a gasket with a wire brush before reinstalling it; wiping it clean with brake cleaner on a rag, tho perhaps.
I DO spray one side of the gasket (the top side) with silicon spray as a release agent to facilitate future removals w/o damaging the gasket. I don't know that I'd use grease, but for sure you want the gasket to stay put, i.e., not squirm around, especially near coolant passages.
I've experience a few gaskets that slid around, e.g., this one was actually the IH/head gasket. Note the gasket has squeezed into the runner, and the coolant too. (This can be a problem with ported runners especially, as the space between coolant and the runner gets narrow.)
This happened within weeks of installation on a couple occasions (note the runners are significantly ported). I had been smearing a film of RTV on the gaskets - thinking that would "help". NOT!
I switched to Jerry's gaskets, and it was he (as I recall, Jerry?) that suggested than the gaskets be applied dry (read: NO RTV, etc to "help").
Now (especially with ported top end) I take great pains to get the metal surfaces absolutely dry and clean with (CRC - red can) brake cleaner and a razor blade, before installing (Jerry's gaskets) dry, except on the IH around the coolant port. There, around the coolant port only, I use some Permatex sealer (I forget the exact part number, but it is opaque, powder blue colored, bonds like glue and seals as well). That seems to have done the trick!
Well, you may get away with it (greasing the gasket(s)). But, if you develop a high idle later, you'll have a pretty good idea where to start looking.
Don't forget the BLUE LOCTITE on the threads before torquing the plenum/IH.