So far joined the free parts of the sites, my experiences so far...
POF - nobody will chat,via emails, unless they see your photo. Some demand a photo. Some rude/crude buggers.
PMF - Silver pond - again demanding photos.
PMF - Single parents - no interest whatsoever
Zoosk - lots of messages although I haven’t written a profile.
It seems I have more luck saying nothing on Zoosk then writing a profile on any website.
I think I will give up.