The internet is full of unpleasantness the same as it is full of worthwhile decent stuff aswell, it always has been IMO. Web users can be easily tricked into clicking through to something they might not want, eg a popup appears saying do you want to instal xyz program, yes or no, but yes means yes and NO means yes and so does the X in the corner, because that was the way it was designed, to trick you. (by the way, if you get that - use ALT F4 to force it to close, don't click the X). It's better nowadays with more modern browsers, that have anti phishing and anti popup etc, and the antivirus and anti spam software is in a constant battle to keep back every new trick the spammers have. But if you end up somewhere unpleasant, just close it down. As far as I'm aware, it would be easy for an expert to tell if someone just stumbled on something or was having a good look.