I got this from a normally greedy dealer for a reasonable price. That is the first red flag. The other is they didn't have it graded. It doesn't appear to be regummed. I know this is a dangerous question to ask here as some of you see reperfing on everything, but has it been reperfed?
Reperf? I am no expert at reperfing, but at first glance, the holes along the right side appear to be a smaller diameter and cleaner cut, thus leaving wider perf tips and fewer fibers extending from the tips than on the opposite side. The bottom looks unusual to me also. The overall margins seem small/tight. Yes, I would study it further.
The bottom is a bit odd in that it appears to have had been perked twice on the bottom, which is more obvious on the left. My opinion is that the right side is not reperfed based on the lower most perf. I enlarged the image to where I could measure the the bottom right perf hole at 6mm. The left side also measured 6mm. The rest of the perf holes on the right look smaller because they are short perfs.
Below is new photo top to bottom left to right. I was not sure how far in to move the floating position against each end. Is the goal to make the end perfs try to align as close to a circle as possible and then check the others. I am taking this opportunity to educate myself and try to improve how to best perform this test while also trying to contribute to the original posting.
Thank you everyone for your replies. I took a closer look at the bottom and I can now easily see where it has been reperfed as there is still evidence of the original holes to the left of the new ones (which quignt nailed). I'm not convinced that it was also reperfed at right, but it doesn't matter since the bottom is bad, so back it will go.
Sinclair - I don't recall calling you out unless you are someone who sees a reperf job on every stamp. It is just my observation that every time someone posts an image asking for an opinion that someone always claims to see something that probably isn't there, that there starting position is there has to be something wrong and it is their challenge to find it. I'm a face person and not a screen name person, so I do a very poor job of figuring out who's opinions I should trust (there's only one I've learned to mistrust).
Finches - where did I call out all dealers?? This particular one is greedy and I'm pretty sure he knew there was something amiss with this stamp (it was one of the few Shanghai's in the group he had that he hadn't gotten a cert for).