MOD: this is actually a very difficult question to answer. There is a huge list of reasons why I may or may not use your original character.  
For starters level of difficulty comes into play. If your art style is greatly different than one scene in the show that means all have to draw your original character from scratch, I did this with ask Backy.  
I was very happy with the results but not every pony original character will convert so smoothly. In fact some you’ll find it’s completely impossible. I suggest that if your person who likes to see his or her original character appear in other people’s blogs you compile several references sheets showing your character from all angles.  
If I can just grab your original character directly from a reference sheet and turn it into a sticker I can move around in use it’s a pretty safe bet I’m going to use your original character on my blog.  
I’d also like to take this time to talk about my view of what’s appropriate on my blog. Though I might be a fan of many things I don’t like to show vulgarity. now as to what I define vulgarity as… that becomes a little bit more complicated. For example milky way, if for some reason milky way appears I plan to show her foal in uncensored. Now as to why this might be there’s a very simple reason. mod thinks there’s a very fine line between censorship and discrimination to censor this particular character I feel would be discrimination however others I may feel was common decency. In the end to answer your question it’s totally up to me.  
But there’s no shame in asking and no harm in trying. so from the mod of Timber the wood pony. have a nice day