Latics had won four of their previous five games, but they were comprehensively outplayed at Boundary Park.
Swindon had already missed a clear chance through Matt Ritchie when they scored in the 28th minute, Raffaele De Vita driving in Ritchie's cross from 10 yards. De Vita struck again just three minutes later as he met Nathan Thompson's cross with a 12-yard shot which took a big deflection on its way past goalkeeper Alex Cisak.
Dickov said: "We are at our worst when we've just had a couple of decent results. Give Swindon credit because they are a good team, but there was complacency out there because we'd won our last two games.
"Our standards dropped and there was a lack of pride in individual performances. That isn't good enough. If you don't have pride and desire and effort, and if you even have some laziness, you will never win a game of football.
"The lack of professionalism is not acceptable, but in the first half especially that's exactly what happened. What's the point of putting on training sessions if some of your players go out and think they know better?
"At best we were bang average and I can't possibly defend the players without making myself look stupid. It's no coincidence that after two wins some of them let themselves down - they got into a comfort zone."
Robins boss Paolo Di Canio was delighted to see his play-off chasing side turn possession into points, and he said: "In the first half we were excellent and we could have scored more than two goals.
"We dominated clearly and it's good to win because we have dominated other games and only taken one point. Oldham have very good, sharp players up front, but we defended well.
"We have Tranmere next and I'm happy that we will play the leaders. Before I was worried, now I'm happy. The fans can go home happy, not just with the goals and the points but also with the professional performance."