There is a bot running around.

This is the account, and it is posting adverts in the troubleshooting dead machines forum.

The spammer has been banned, his postings all deleted.

i think that phone guy was a bot too

The spammer has been banned, his postings all deleted.

He is online currently, can banned users are able to login ?

Banned users are able to log in and have access to everything guests have access to. It's silly for someone to have less access when logged in than when logged out, otherwise they'd just log out.

also such banned users may need to contact mods to contest thier ban, so require the ability to login in order to send pms

Banned users can't send PMs.

Nope. That is just the way it has been when I got myself banned.

Banned users can register under different name and thus bypass the ban. Only the account gets banned here. There is always an IP ban option, giving that the spammer has a static IP address (which is highly unlikely), but Dani refuses to go that far, because of the possible collateral damage. Here in Croatia, one has to actually pay extra for static IP address. All I need to do to change my IP address is to reconnect to ISP.
But, if the spammer is using my ISP, it is possible, by banning his IP address (in reality, ISP server's IP address), to ban me as well.

chaky got banned?

Oh, yes I did. You can ask jwenting.

Yeah, but not for long :)