It is entirely possible that both karmajunkie and giaour are right. The dispersant could have: a) obscured the environmental damage and b) contained the dam

It is entirely possible that both karmajunkie and giaour are right. The dispersant could have: a) obscured the environmental damage and b) contained the damage to low-impact areas Now in this particular case I think the trade-off was completely worth it. That's because the sea-shore is one-dimensional whereas the sea-floor is two-dimensional. An amount of oil that could damage a huge fraction of the Gulf coastline can damage a much smaller fraction of the Gulf sea-floor.