The only stations I actively avoid are Stewart's c-stores around here, it's a NY based chain and they're absolutely everywhere around here. Probably 75% of the time I fill up there, the bike runs like ass.
I've heard(haven't found any proof), that Stewart's buys "leftover" and bottom-of-the-tank gas from suppliers to try and save money, and that the quality there is generally pretty bad. I've got no proof, but I know I'm not the only one who shares this opinion, and it's happened way too many times to be a coincidence.
When possible, I try to fill up a larger, name brand stations since they likely turn over gas faster, and the fuel you get is more likely to be fresh. Some of the big 10+ pump stations often get fuel shipments every day, often selling over 10k gallons a day.
Unfortunately, I don't thing E10 is going away anytime soon. The cacks in Washington who all jumped on the big ethanol craze a couple years ago signed in all these bills to heavily subsidize corn for fuel production, and now if they backed out all the farmers would be pissed. And of course politicians never admit they made a poor decision based on junk science and short-term views. E85 is still hardly widespread, and around me only a 10-20 cents cheaper than gas from all the gov't subsidies, since it's actually more expensive to refine and produce.
Next time you go to a E10 station, take a small sample into a clear jar or bottle. Let it sit for a bit. Does a layer of water materialize at the bottom? If so, the fuel in the station's tanks is already "phase separated". If not, adding more alcohols(heet) isn't going to "dry" the fuel at all.
Looking at the MSDS for seafoam, it's made of three ingredients. About half pale oil as a base, 30% naphtha (aka mineral spirits/paint thinner), and a splash of isopropyl (rubbing) alcohol. You could make this stuff yourself.
Another rumor is that big-name chain gas stations only put ethanol in the "regular" gas, while midgrade and "premium" gas are pure gas. I know this one's crap, since the laws that require E10 say it has to be in all grades sold, so spending extra for premium won't help either.
I've never noticed an appreciable difference between pure gas and E10 in anything I have. Snowmobile, boat, jetski, quad, motorcycle. They're all rated for up to 10%. Maybe I'm lucky.