Some domestic appliances can generate high voltage spikes when components inside them "switch" on and off.
To overcome the potential for these "spikes" to damage nearby equipment the designers include a filter on the mains input in an attempt to eliminate or at least reduce the voltage spikes.
Mains filters - by virtue of their construction - can allow a small measure of leakage - it's what they're designed to do - let the high voltage transients leak away harmlessly.
My guess is that your test engineer is misinterpreting the output of his test equipment - it is not unusual for some equipment - by virtue of its design - to have a small amount of leakage.
Tower computers also have these filters to stop any spikes coming in and destroying the delicate electronic components.
If the properties have RCD earth leakage breakers on the distribution board - and they are not tripping - then you very probably do not have a problem.
To have three different washing machines all exhibiting "dangerous" conditions is beyond normal probability.
Seek out a test engineer who understands these things.
Good luck...
Peccavi
February 2011