I want to know if I register domains such as www,casiowatches,com and www,casiopathfinder,com (pathfinder is a casio model) could I get into trouble for building a site around these domains ? (I know both these domains are taken but I'm just asking as an example)
Yes, you can be sued for trademark infringement and both examples are clearly infringing upon the mark holders rights. You can't use trademarks in a domain when it is used in the same way as the trademark holder. A domain name like casiopoolcleaners would be a lot less likely to create consumer confusion (and as long as it wasn't about caiso products) - although famous marks have even more protection than a regular trademark.
@OP: please do not show your domain names on the public. They are not registered yet and they can be grab by other people and you might lose them.
ok what about domain like casiowatchreviews.com. would that be ok ? @serverpoint - they are registered
That domain is in a more grey area. "Reviews" sites have been involved in trademark infringement lawsuits (dswreview.com for example). I wouldn't use a trademark in a domain unless you have permission or are prepared to spend tens of thousands of dollars in legal fees if the TM holder decides to sue you (do you want to spend $50K or more to keep the domain?). Stick with a generic name that doesn't contain a trademark - like "bestwatchreviews.tld." Legally, you'll also need permission to use any photographs - even if you are selling the product.
They are not good jokes with such big guys as casio. Do not go for that. You develop it and then they come to you with lawyer and take it.
The search function is your friend! This thread should leave you in no doubt at all on this subject: http://forums.digitalpoint.com/showthread.php?t=1088058&highlight=trademark+domain+names As it so happens, 15 minutes ago I wrote on this subject on my domain blog which you can read by clicking the link in my signature. I put the position to you, very clearly with no mincing of words. Best regards! Mark