Going back to GCII, I would usually leave Mars uncolonized because I knew it would be colonized by somebody and I would flip them. This was basically my strategy for all low quality planets.
As for being another species, I am not a racist and they are welcome in my empire (this is just a joke and not a shot at the OP)
I colonize more low quality planets now due to the shipyard system, but I still don't mind flipping any AI silly enough to move in next door. I see a lot of conversation about OP culture flipping in GCIII but to me it is just as hard compared to GCII and maybe even harder. Frogboy commented that the culture buildings are over powered and this might be true. In the late game I do see very rapid expansion into the AI ZOC if I have been building (spamming) a lot of culture, but once you start enveloping them they don't flip any faster in GCIII than they did in GCII (IMO). On the other hand, in GCII culture star bases were very powerful. In GCIII not so much
I think a lot of the conversation comes from a player element that hates culture flipping in principle and would like to see it out of the game entirely. That is okay, everyone has a right to their opinion. The same element complained just as loud in the GCII forums and some changes were made but not much. I think it is great that GCIII will be so modable. We will be able to tune the game to our own choices and for those not inclined to do mods, I am sure the mods will be available for download by everyone.
BTW, present company is excluded from my comments about hating culture flipping. I am referring to an element with much stronger feelings on the subject.