There have been a few small time local beers that I have gotten seaweed or very doughy off flavors from (never together). I just figured that they weren't very good at what they were doing. I never got it from a widely released brewer. Lately, I've had more of both. There are two that bother me the most. One was a great series that claimed to be the same beer, with a different hop bill each time. From that, I got a ton of the doughy taste (at least two in the series). Tonight's, was a beer that I thought was incredible on tap. Pure hops, no malt. It had been canned a few times and I went to the brewery on the day of it's latest release...both dough and seaweed. I've been accused of picking up flavors that others don't taste, but these two flavors push it towards a drain pour (hasn't happened yet). I've never seen any mention of these off flavors. Anyone???...
The only seaweed-like thing I've come across was from a "sour" -- a Jolly Pumpkin farmhouse ale -- and it was enough to make me think the tap line hadn't been cleaned. I've never been able to confirm nor deny, but if the tap line was clean and the beer tasted the way it's supposed to, then it can be chalked up to the beer being in that American-brewed farmhouse/wild ale world where almost any kind of note can turn up, seaweed included. If the "doughy" note you're describing is anything like what I call "creamed corn", then it's dimethyl sulfide (DMS) and from my experience it definitely can grow over time (hence you might find it in a canned version of a beer that tasted fine fresh out of the vat). If the "doughy" note is not like creamed corn, then it's possible it's from crystal malt taking over the beer ... or from any combination of malt taking over the beer. I've not run into anything off that I would call doughy. Really good pilseners and English pale ales often have a huge bread-malt (bread dough in some cases) flavor, but I'm assuming that's not what you're talking about.
