Cheating In Mining?

I`m not sure about this topic, however I have seen some talks about cheating in mining in chats.
People talk about ability to join to block almost in the end and to increase capacity . In such ways they can take the biggest part of rewards.

And there some questions... How can it possible? Do owners of pool effect on it (is it possible they give somebody information?)? Or may be somebody make this mess in purpose?

I doubt about such tricks, nevertheless such talks have place to be. What do YOU think about it?