Having just returned from what was a most fantastic and enjoyable first trip to Prague, I must warn readers of a professional rip-off scam on the underground.
I asked at the ticket office for a train ticket for one stop and was charged 4 Kc [15 cents]. As I started to leave the next station, a plainclothes inspector walked straight for me, produced his badge, and asked me in English for my ticket. I was told this was a child's ticket, and he demanded a 400 Kc fine. I was obliged to pay.
I would state that this inspector was advised to look out for me by the man at the ticket desk. From all the people, why me, and why were his first words in English? I complained to the Tourist Office by Charles Bridge. They said they heard this story many times from tourists, all having been sold a child's ticket!
I then made some investigations and observations and noticed that indeed, tourists were targeted and fined. If this were a European Union country, I would have a field day prosecuting those who are prosecuting illegally.