well when the end up the plug is brown it means its running good, if its black it means its getting to much fuel, if its whit it is to lean not enough fuel, sounds like u may need to adjust the carb give it a little more fuel not much cuz as u stated there is brown on them and that means its running well but sense theres white on it, that means its to lean so adjust your carb to give it a little more gas and you should be alright, good luck
your mention of brown sounds normal. The white speckles and white electrode could mean the plug is too hot. Make sure the plug you are using is the correct heat range. Other causes could be overadvanced ignition timing, lean air/fuel mixture, vacuum leak (intake manifold), sticky valves or insufficient cooling.
Is the engine efi or carb? Have you changed anything lately such as the intake or carb? Are the correct spark plugs being used? Have you messed with the timing? Anything out of the ordinary happening? later
Thanks for the usefull information. Ill look into all that stuff. I thought that the tip of the plug was not acually were you were supposed to be looking though? More like down at the base of the plug?