I did say my worst season was season 13, but looking back, it's not entirely true, there are a couple of seasons I did not enjoy, but to really pick one that is the worst of the bunch is not easy
Here are my bottom five (in no particular order):
Season 7 - this season for me, marked the end of the "classic" amazing race era, mostly due to the fact that this season could be renamed "The Romber Show" , but watching it I don't get the same sense of enjoyment and wonder I get when watching the first 6 season, the route was very forgettable (quoting StephenWasHere, "wayyyyy too much South America") the teams were mostly underwhelming and/or not very rootable imo (except for Uchenna and Joyce and Meredith and Gretchen) and to have the race not circle around the earth was a letdown, a disappointing season all around.
Season 9 - I can't stand this season, I sincerely cannot stand it and for two simple reason, Eric and Jeremy and BJ and Tyler. I have nothing against the two teams, but their constant 1st/2nd place finishes was extremely irritating and took out all the excitement that we've come to expect from the amazing race, in fact the casting was terrible with only two extremely rootable teams (Dave/Lori and Fran/Barry). To be fair, the route was decent (dare I say good?) but not executed very well and the tasks were at times interesting and related to the country they're in, but I remember not enjoying this season and it is the season that nearly made me stop watching the amazing race (thank god for season 10).
Season 13 - It's safe to say that in my opinion, every single aspect of this race was bland (not necessarily bad, just bland), casting, route, task, editing, everything. The teams were all very generic teams with not much unique or special about them, I liked Ken and Tina but when it's against a field of teams from the Amazing Race 13, that's not a really big accomplishment. The route was god-awful imo (apologies to the producer), all the countries are interesting places (New Zealand, Cambodia, Kazahkstan, Russia, India, etc...) but when put together, it just doesn't work, the result was excruciatingly predictable that no amount of editing could save it. Unfortunately, this was the second time a season nearly made me stop watching the amazing race (once again, thank god for the next season, season 14)
Season 15 - Like season 13, a season that's bland in all aspects, perhaps not quite as bad as season 13 but still pretty bad. The teams this time are more colorful and unique, but at the same time still not very memorable (except for Zev and Justin, the poker girls, and Brian and Ericka). The route was also awful (again just a little bit better than season 13) because it has interesting locations, but it was all executed very poorly and putting these countries together was not a good combination. I never felt really attached to this season even though I did watch it to the end and this was a time when I was really worried about the amazing race because of it's degrading quality. But one thing's for sure, this can't be my "worst season" since it's just a little better than season 13.
Season 16 - this was the season that seemed to confirm my worst fears, the amazing race is ... ... "mediocre" *shriek*. I mean, I give casting the credit of selecting what would become one of my all-time favorite team, Jet and Cord, but what casting talent they used on Jet and Cord, they seemed to have exhausted the rest for the other teams. The cowboys were the only team I liked in the final 5, and the only other team I did like was Steve and Allie because they were pretty benign. So that means that out of 11 teams, I only liked 2, wow... just wow. besides that, the route was uninspiring (this is huge for me to say since it visited my country france) the tasks seemed too simple and overall it's a season I defined as "generic" in all sense of the word.
So what's my view on the Amazing Race now? well, luckily the Amazing Race gods were with us when they brought us season 17, the best season since season 12, it gave me another one of my all-time favorite teams, Brooke and Claire, and a lot of other extremely likable teams (except for the male members of all the dating teams), it was great. Then came UB, which, while not as good as season 17, is still an extremely solid season and to be honest, seeing returning teams was a real treat. Here's to hoping season 19 will not disappoint...cheers
*this is all strictly my opinion only*