It's perfectly "legal" to register anything that's available as long as you don't do anything "illegal" with it. You can see WhiteHouseUsa.com being sold at GoDaddy. So, if you happened to acquire WhiteHouseUsa.com and tried to develop a PORN website on that name, then you are in big trouble.
Some people are frightened of others' trademarks but even trademarks are limited to a vertical, a trademark can not be a sweeping trademark that encompasses a word/keyword/concept in all verticals.
As for the "intent" of registering a name, who knows about it except you? It's for the complainant to demonstrate bad intent, if it ever comes to that (UDRP etc.).
If you ever happen to realize, at behest of a trademark owner, that you are actually infringing their trademark in their vertical, make peace with it and sell it to them for low-mid $x,xxx.
Trademark holders try to run you down mostly when your name is hurting their reputation and/or business.