(Please see update below)
I am always amused by how even those companies you would think wouldn't stoop to the foot-in-the-door tactics of spammers, do. Like this one from IBM, at the foot of a submission form -- specifically for journalists, no less:
(The text reads:
This data may be used by IBM or selected organizations, such as Lenovo, to provide you with information about other offerings. To receive this via e-mail, check the first box below. Alternatively, if you would prefer not to receive such information by any means, check the second box.
Please use e-mail to send me information about other offerings.
Please do not use this data to send me information about other offerings.)
Why, specifically, two separate check boxes? What happens if you check both? Have you committed yourself to both receiving emails to get information about other offerings, and yet not allowing IBM to use this data to contact you? That would at least be a challenge for them. Leave both unchecked IBM cannot email you about other offerings, but they can use the data you just gave them (namely your email) to send you information about those exciting other offerings.
I urge you all to send them a query on their main submission form trying out both, and let me know what happens.
(Update Nov 2 2007: IBM have agreed having two checkboxes is confusing and unnecessary and promise to remove it. I have also tried leaving both unchecked, or checking both and error message is returned. So upon reflection I don't think this is a fair example of Sleazy Checkbox Syndrome and I take back my harsh words about Big Blue. It's poor form design, but it's not done to confuse the user. Interestingly a more egregious example I recently cited also seems to have disappeared, as far as I can work out. Laplink have yet to respond to my request for comment.)