The term 'Shady Salesman' can be summarized as a person who engages in unethical or illegal activities to make a profit. This term is often used to describe someone who sells goods or services without proper authorization or who uses deceptive tactics to make a sale. The term 'SPIV' is a slang term for a shady salesman, originating from the British underworld in the 1940s. It is used to describe someone who is involved in illicit activities such as black market trading or other forms of fraud.