I was a member for a couple of years.
Never stayed - but hosted quite a few folks.
Most were quite nice - a few rude -
Such as showing up drunk or having to be asked to get a move on.
(What is so hard to understand about - "I will be leaving at 8:00"?)
Last year, I randomly checked out someone.
His name - not absolutely unique, but fairly uncommon -
Was the same as someone convicted of sexually molesting frat pledges.
I did a thorough web check - his blog site confirmed identical details.
When I brought this to the attention of the Warmshowers director -
He said that it wasn't their job to screen persons using the website.
Maybe there are only a few risky folks - but it only takes one.
Plus, websites such as that DO have the potential to attract sociopaths.
Sorry, but that is how sociopaths think and operate.
They actively seek out persons who may be trusting or vulnerable.
I immediately ended my participation in Warmshowers.