is it true?

[USFlashMap.com]

that it is possible to "hide" key words behind the pictures and escape spiders?

[Micheal Pannell Realtor]

alt tags, but i dont think that is what they are for

[USFlashMap.com]

but alt tags are also searched by spiders, aren't they?

[Bigtoe]

Why would you want to hide keywords from the spiders?

[VRI]

I think what he's referring to is hiding keywords in text behind images (viewable to search engines but obscured to visitors), and yes it's possible but not recommended.

[BrandonSternfield]

Alt tags appear when you mouse over the image though... so if you mouse over a picture of a property, and you see like every city you work on.. they might wonder what's going up.

The alt tag is used to describe the picture.

[Sam Chapman]

A wise use of alt tags is fine. If you use them to stuff KWs you will find that to be a bad practice.