It's pretty thorough. A few things people have noticed is numbers in the background/text being altered, the position of the dofan watermark on the page changing, specific letters in the text being partially cut off/greyed out, and numerous other details. I don't think it's possible to get rid of all of them unless you buy at least 2 copies and know what to look for, and even then it's risky.
As much as we'd all like new comics, don't risk legal trouble for us unless you know what you're doing. And definitely be wary of anyone offering to do it for you, because forums like these are often filled with spies.