Maybe not the right place but seems there are several web experts here.

Can web spiders read and harvest e-mail addresses from a pdf file ?

It's certainly possible.

I don't know to what extent it's actually done. In principle, though,
any file which stores information as text can be searched (Google
apparently searches PDFs and indexes their contents, just as if it was
in HTML), and a spammer/harvester could do the same thing, though.

I have my doubts as to whether spammers really care to go to that much
work, though.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!