I haven't watched Press TV myself except for the odd clip but what I hear about it is that it is a propaganda channel run from Tehran, and that to appear on it you have to be highly uncritical of the Iranian government. According to the journalist Dave Osler (comment 12):-
I am generally of the ‘bus company’ theory when it comes to media outlets. Who cares who runs the bus, so long as the route takes you where you want to go?
That is why I have in the past written for the Daily Express, and happily appear on rightwing TV and radio shows (Richard Littlejohn, Nick Ferrari etc) if they want a leftie on to spark debate.
If the media offers you a platform, take it, on the sole condition that you get your message across.
But the point is that Press TV doesn’t offer that kind of platform, It carefully selects Brit lefties that will say the sort of thing that complies with its editorial line. That sort of exposure isn’t worth having.
So it's no surprise that Press TV employs islamist and theocracy pimps like the well-known hijabbed sister-in-law Lauren Booth, Yvonne Ridley and, of course, George Galloway.
Radio 4 ran a programme about Press TV on Thursday evening, which is well worth listening to.
I would have liked to have heard more about Press TV's audience. I would guess that it would mostly be islamist sympathisers, and the kind of member of the far left who a few decades ago would have listened to Radio Moscow as their in-depth unbiassed news source. For example, here's a thicko who comments at Shiraz Socialist (comment 5):-
Many Marxists with decades long experience in the movement have contributed to press tv, which in content and form, beats the superficial news churned out by media that Hitchens whored himself to.
George Galloway was invited to appear on the programme but did not take this chance to defend his employer. He's not usually shy about appearing on the BBC. However he might have been asked impertinent questions which is not the kind of thing his heroes eg Stalin, Saddam Hussein and Bashar al-Assad, would have put up with for a minute.