I don't believe most that I see on TV, especially when they talk about nutrition. If I believed what the mainstream media told me, I would double, maybe treble the amount of carbs I eat, and have about 30%of the protein I eat, 'cause, you know, it makes you fat and destroys your kidneys and all that saturated fat in meat will destroy my heart. I would change my training from low rep heavy stuff to high rep light stuff, do some aerobics, and bounce around on stability balls and vibrating plat forms, because, 'research' has shown these things to give you a much better work out...
On a half serious note - I done a search on the PN forums for 'fish oil dosage' and loads of results came up, complete with references. Done one on Google Scholar and loads of results came up, a lot of them seemed to be on people with athritus, but I only glanced, really - do some searches, have a look through them, see what you find. Personally I don't need any convincing.
I can't help but wonder what's wrong with the 'credibility' of a recommendation from Precision Nutrition/Berardi, who actually do a lot of research themselves... Not to mention the likes of Charles Poliquin (30-45g / day!) - guys that, day in, day out, make people stronger, bigger, leaner, healthier, or whatever, and have done so for years.
I do feel that people can get far too caught up on the 'research' (whatever they define that as).
Also, when was the last time you were drunk? I hope you checked the research before you consumed excessive amounts of alcohol. When was the last time you had a Pizza? Excessive carbs? Did you check the research before hand? Fish oil is just fat, it's not like it's morphine, you know....
My opinions is basically this - 10g of fishoil is far from excessive. If you're going to ponder what excessive amounts of it do, you first need to define what excessive is.