3 domains share products users etc 3 different stores

[dgent]

Well it wouldnt cause issues, yes all the sales would be logged on all sites. Paypal always redirects to the correct site, thats nothing to do with the database.

Ive done this exact thing. I have three dress sites running off the same database, one is focussed around body con dresses, the other designer dresses, and the other clubbing dresses. The three sites have different looks, and ive done some clever coding with php so the two other sites modify the keywords on the product names and their descriptions, so they all show different content. Ie 'Black Body Con Skirt' will show up as 'Black Designer Skirt' and 'Black Clubbing Skirt' on the other sites, like wise substituted words in the descriptions, metatags, everywhere, and google indexes each site independently with no duplicate content.

Allows me to have different content on the net, selling the same product, and without diluting my keyword content level on each site. Great thing is all the updates on one site affect the others, so simple to maintain.