Is it bad to run rich?

Went for a squirt just before, coming back my mate said I'm blowing black smoke out the back in VTEC. Bit of a search on ht.com says I'm running Rich on fuel. Car was fairly warn (was only a 5 min quiet drive, usually I like to ger her at least 10)

Mods are: i/h/e, dyno tuned s200, flywheel and clutch.

If it is running rich, is it bad? Could it be a sensor out of whack thats causing the the fuel maps to be wrong? It was recently tuned (6 months ago) so I can't imagine it was tuned purposely to run rich or is that a normal thing todo? (BLKCRX tuned it)

Matt