What's up with shampoo?

I hoard several things and one of them is shampoo, don't know why. I hoarded shampoo even when my hair was only "longish"; now it's very long. The funny thing is that I have no preferences in shampoo, and don't really notice much difference between shampoos. I just enjoy having lots--and lots--of choices, and rarely use the same one twice in a row. Consequently I rarely finish off a bottle.

Stupid pictures! I started a Google Picassa account just to post these pix on this Google blog! No idea why they aren't working. Click on the space to see the pix if they're not showing up.
Take note of the tall red bottle of shampoo in the middle of the middle row, next to the bar of soap, in this pic from 2007. I can no longer find that bottle.

See the 4 square red bottles on the shelf at the right? Here's an even better pic of them from 2006.

One of those bottles was immediately conspicuous by it's absence.

The bottles on the edge of the tub had been rearranged so i don't have a pic of the red bottle and green bottle that aren't there any more.

I don't think I'm imagining this. I'm pretty sure they were there in their usual places when I left.

I've obsessed about shampoo before on this blog, about leaving a bottle behind on one vacation, then looking for it, and replacing it, on a subsequent vacation. This time I left one, a store-brand knock-off of Pert + conditioner, behind on purpose, with no regrets. I hope. It looks lonely.