She says as long as your not too elfy 
The only Inquisitor she's truly happy to see is the qunari one
I missed this response last night because I was very sleepy, so I'd like to adress it now.
When Sera meets your elf character, she says „aand you're an elf” (spoken with disdain in voice and with disgusted face expression), followed by „well, hope you're not too elfy”.
So it's very clear it was about Inquisitior being elf on itself. Also, in one banter with Iron Bull, when he asked her about her thoughts on some girl they saw in last town that catched his eye, she said „too elfy”. So it was apparently about her physical appearance, definitely not about her views on elven culture or anything that is used to excuse Sera's behavior.
Lately I've seen fragments of „White Chicks” again and realized why was I having feeling of deja vu. I think those who watched that movie know what I'm talking about. But that character was written to be a comedic caricature to be laughed at, when Sera never gets called out on it, and because game does everything to sh*t on elves it even looks like her prejudice is justified. Definitely saw people defending Sera by that argument, which is really terrible on itself because in the end, as with every decent work of fiction, it's in fact about real life issues.
On TV Tropes this particular trope is called „Boomerang Bigot”, and turns out, someone already listed Dragon Age Inquisition and Sera in video games examples there.