I think you must be running reasonably good oil, I'd rather find thick goo than abrasive carbon let behind by decomposed oil.
Thus seems normal to me and preferable (IMO) to dry gritty abrasive carbon actually. I find I must clean my RAVEs at least once per season and often twice, this is a 951 carbureted motor that sees between 1~2 hours per weekend during the season, not what I would call heavy use.
Or it might be possible you're running a castor bean oil, in which case stop doing that. I doubt this though, castor doesn't work at the higher injection ratios we're running.