Even thought Prague is a capital with quite low crime, there are plenty of scammers in the city centre. Mainly they are foreigners and they concentrate on the tourists. It's a big business, so be aware of them. Unlicenced guides offer free tours or so called charity tours, they live of tips and pay no taxes. Other guys lend you snakes and colorful doves for paid photos - that's actually considered as animal abuse. Some taxi drivers have fixed prices that are often 3-5 time higher. The vintage cars are not vintage at all and they produce tons of pollution. Beggers are professionals that often kneel or have little puppies with them. Physically handicapped people beg or try to collect money for charities but they are suddenly healthy once they leave the tourist spots and act agressive when confronted. Middel aged men helpfully exchange money on the streets for East-European currencies that are worth nothing. Pickpockets accidently bump into you or use small children for the dirty job. And some salesmen in the little grocery shops have double prices... The city of Prague and the Police are doing their best to get rid of these people but often the law isn't strong enough or they find new ways, so it's a long shot. But this is happening all over the world. So, better safe than sorry.