I've seen it for Venezuela and Syria, but i'm sure i could find this for quite a lot of other countries.
We're usually saying that it would legitimize these elections, and are asking instead that the opponents boycott them. We can continue to criticize the biases surrounding the votes instead of the votes themselves if that's the problem.
Some leaders may believe that the processus of elections is biased because unjust external pressures are putting a strain on the country and strengthening the opposition ; but, despite that, some of them are still asking for international observers, which could be an occasion to seize, instead of refusing to send them yet accusing them of cheating.
So i wonder if i'm missing something by thinking that we don't want to legitimate the whole process by counting the votes.

For them it seems like it would be the same if they're already asking, but for us it could open our societies to accusations of double standards since it could be argued that our own elections aren't perfect.
In the end sanctions would stay in place so it wouldn't be useful in any way, and doesn't matter, i should probably delete this post but i'm leaving it in the off-chance that some find an interest in it.

If you had the initial thought that international observers won't prevent cheating : they would count in double the votes, with the venezuelans of their area, and have everything under their eyes from the beginning of the vote to the end of the official count, so i don't see how cheating would be possible.
For now, our version is that they're miscounting the votes, yet we're refusing to send such observers.