I didn't think of the word, 'scavengers', as derogatory, Rose. It has more than one meaning, in some societies it is considered to be highly entrepreneurial for people to scavenge and find things worth something.
From wiki: A mudlark is someone who scavenges in river mud for items of value, a term used especially to describe those who scavenged this way in London during the late 18th and 19th centuries.
Very enterprising!
Yes, it is interesting, must be wonderful to find something of value or even a small coin purse full of money!
(If I did it, knowing my luck, I'd find old socks, combs and condoms.)