Speaking as someone who's a little "out of the loop" with anime (which I think is kind of good in this situation, but ah well)...
Let's look at the Pedobear cosplay vs the nazi cosplay I saw sometime during the con.
I know who pedobear is, I know who cosplayed him, we are sort of friends/acquaintances. I thought the joke was hilarious. I had no issue with it. Anyone covering Kumoricon who snaps a picture with a giant bear is going to think one of the following things...
A) He's a giant cuddly teddy bear.
B) He's a furry.
C) He's an internet meme.
With A! There's no problem with that whatsoever. If it's portrayed as being cuddly in the article, it's cuddly. Congrats, K-con is kid-friendly and entertaining to kids.
B! Furries are a little different. While I am pretty sure most of them are very good, wholesome people (exchanged a few words with one while waiting in line, she seemed nice and friendly enough), furries generally are not known for being kind people. Often, they are considered below people. I'm sure any article talking about this would reference the CSI episode at least once, and at least one...interviewee might say how all furries are sex-crazed homosexual animal abusers. Or at least, to a lesser extent. The idea would be there. If we didn't want this image though, all furry costumes would need to be banned... This doesn't affect me in any way, but it's still unfair to the majority that doesn't go around kidnapping sheep and whatnot.
C! First off, the reporter will need to know the joke to recognize that Pedobear is, indeed, a pedophile. And here's the thing... If they know the joke, chances arre they will know that it is, indeed, a JOKE. It seems VERY unlikely to me that any random reporter on the street is going to recognize a bear as being a pedophile and think they're serious. Of course, I'm not involved in the news world too much, but really, use some common sense here. While it is very possible this idea could be brought up, the ONLY WAY the reporter could identify the bear as being a pedophile was if s/he knew it was a JOKE.
Now, for the nazi whatsits. I haven't watched any anime involving nazis, and seeing a cosplayer dressed like this made me do a double take and disturbed me a little. I recognized it was a character since there was a skirt and all that good stuff, but honestly, this DID BOTHER ME.
How many ways can news reporters see a nazi character at an anime convention?
A) They're an anime character.
B) They're an anime character promoting genocide, interracting with a fairly large group of younger, impressionable people, possibly off-con space in the park...
Can you see where this is going?
The nazi costume I saw was well made, what I did notice of it. Regardless, it was still shocking and...as I've said, a little disturbing.
Someone else has mentioned random people on the street recognizing this and that, and...okay. EVERYONE EVERYONE EVERYONE knows who the nazis are, and can identify them by their swastika arm bands (which was how I recoginzed them). Someone who sees a full-sized bear walking around an anime convention most likely won't think of the meme at first! They'll think "Oh, there goes a furry." I KNOW that if I hadn't known this person was going to be pedobear beforehand, that's what I would have thought, and while I don't frequent 4chan, I do go on Encyclopedia Dramatica a lot. I know the character, I've seen the pictures, and even then it wouldn't have registered.
...so yeah there's my two cents