Maybe they’d colonized all the other planets with resources and this was the next on their list. The real problem is not so much that they had a sensitivity to water and came to Earth anyway. The problem is that they did so without wearing HAZMAT-type gear to protect themselves. All they had to do is wear a suit like you saw in Outbreak and they would have been kicking some serious human ass, supersoakers or not. [/quote]
But since they have the technology and know-how to get to another planet, don’t you think they’d take the proper precautions before setting foot on the soil, like wearing suits you described? Our primitive species even figured that out before leaving the planet.