Hard situation puzzles

At one time, the following warning notices appeared on one of the main squares of Prague, “Attention! Beware of pickpockets!” The local police knew that there really were a lot of pickpockets here, but they actively tore these notices down. Why?

A man goes to the auto repair shop and asks the mechanic when he is available. The mechanic says he is busy for the next 2 hours. The man thanks him but doesn't return. A few days later, he asks him again, the mechanic says he is busy for the next one hour. Again, the man doesn't return. Next day the man asks him again and the mechanic says "You are lucky, 5 minutes and I'm available" but the man leaves anyway.

A coin collector finds an internet advertisement about a coin collection at a very low price. After reading it carefully, he decides to buy it. Although it is genuine and its value is much higher than the price he pays, he is not happy but very angry.

A young woman has her photo taken with her grandfather, but they have never met before, and neither of them is aware of their relationship.

King George IV was born in 1763 and ruled England from 1820 to 1830 when he died. He wasn’t an outstanding ruler but is known as a footwear trendsetter. His shoes were fundamentally different from those worn by his contemporaries. Everyone liked this innovation so much that today it’s a common practice, which can’t be said about those times. What kind of innovation is it?

The woman is speaking something and she is upset. Nobody can understand her but a man is filming her on camera. Why? And what is happening?

A man designed a device into which you can insert colored paper, and then get the ideal 100$. Experts can not distinguish them from the real ones. How does he do that, and why does he sell this device?

A man woke up at night feeling thirsty. Then he turned off the light everywhere and went to bed again. In the morning he woke up, looked out of the window and yelled. Soon after he committed suicide.

A woman asks questions to her friend - a policeman - about a strange death. After 5 minutes the policeman is surprised to see that the woman finds out the cause of the death.

He wasn’t hungry, but food saved his life.

A professor didn’t want to accept a student’s paper. Student: “Do you know who I am?” Professor: “I neither know nor care. And don’t try to frighten me!” But the professor still accepted the paper. Why?

Bill always wore a silk scarf to work, whatever the weather. What’s his job, and why does he need this scarf?