Why the name flea market?

最近では週末によくフリーマーケットを見かけますが
フリーマーケットを「FREE Market」と勘違いしていませんか？
正しくは「FLEA Market」です。
今日はChristinaが「FLEA Market」の語源を教えてくれます。

It suddenly dawned on me...
why the name flea market? So I did a search
and found a couple of explanations that
sounded believable. Apparently, flea markets
began in Paris a very long time ago -
actually in the late 17th Century in France.
The markets were all in the open with no
shelter. Some of these markets were set up
in gardens and fields. People from all walks
of life bought and sold clothes that were
second-hand. But they were mostly full of fleas.
Even the flea markets in the　alleys and slum
areas of Paris were famous for fleas. So today
Japan also has flea markets, and interestingly
the translation means: nomi=flea and ichi=market.
Fortunately, Japan sells clean clothes and
so does Paris these days. Next time you visit
a flea market remember it began as a poor,
unclean bug event!

Dawned on me=Sudden thought
=〜と気が付く
flea market=のみの市、フリーマーケット
Flea=A bug with six legs that is a pest to both
animals and humans
Apparently=This is used to describe what people say,
but not always true
=一見したところ、どうも〜らしい
All walks of life=A great expression used to describe
all types of people
=あらゆる階層の人々
Second-hand=Not new, already used
=中古で、人つてで
Alley=A back or side street, usually a little dangerous
=裏通り、露地