Elsie has a reputation for turning a decent chap into a complete hooligan at the mere twist of the throttle. When the rider dismounts, they quickly turn back into a normal person. The grin, however, does take a bit longer to disappear.
I followed the progress of a chap in the USA as he rebuilt his first Elsie. Over about a year, he made frequent and polite requests for technical information and spare parts. One day, there was a very uncharacteristic message: "Holy freaking sh*t. Now I know why you guys love these machines!". He had completed the rebuild and taken his first ride.
The fun is not just because she has high power at high revs, but, paradoxically, because she has low power at low revs. The result is that she is very docile until, at a certain point, she suddenly gets the bit between her teeth and screams for the hills. It is almost impossible to resist the urge to get to that point, where the world suddenly distorts in a blur of acceleration and dissolves into a manic scream of power. The effect is about as subtle as riding a sawn-off shotgun, and about as addictive as heroin.
That is about as close as I can get to explaining the Cult Of Elsie.
Being a two-stroke, Elsie is designed to burn oil, which leaves a trail of smoke behind. This has become a kind of trade mark and is highly prized. More smoke can be provided by a "burn out": you spin the rear wheel while the bike is stationary, holding it still with the front brake. The rear tyre heats up and smokes, and is destroyed fairly quickly. That is what the picture on the home page shows.