In the past I have noticed some companies spamming links to online spreadsheets then linking out to their sites from the spreadsheet. I don't know if it still works, but it seemed to be working back then. It's not a widespread practice (at this time)...
The contents are most definitely read. You can search for excel documents in Advanced Search mode.
Msg#: 4368375 posted 7:40 am on Sep 29, 2011 (gmt 0)
The certainly index the links. I have an online spreadsheet on one of my websites and I just tried searching for a unique string of text from it. Up it sprung along with links to sites that had copied it!