Yes, I would, because I think it's interesting. I'm Jewish and I certainly stare/look at Orthodox Jewish women in modest dress, because I'm curious and interested, as it's a completely different way of life to mine.
I was on a bus several years opposite a woman in very conservative dress (not sure the correct term, but where you could only see her eyes). She lifted her 'veil' to adjust the earpiece for her phone when someone rang and I saw her face. She was very pale-skinned, freckles, ginger hair, not how I admit I 'expected' her to look. And I thought about her for quite a long time. I was really interested in knowing more about her story, if you will. I probably did stare.
Similarly, there was a woman in a town where I used to live who wore a full body/face covering. She wasn't, from what I learned, Muslim. She just chose to wear it for whatever reason. I thought it was interesting. It was quite a traditional area (as in White British and a bit backwards) though and I can only imagine she probably did get quite a bit of harassment.
But I think it's okay to look at people and to wonder about them and their lives, but I'd hope it wasn't 'staring' as in trying to intimidate people or make them feel uncomfortable. It's just interesting when you encounter someone who doesn't fit your assumptions. I think people saying they wouldn't stare or think twice about it are being a bit silly, because I think most people probably would, even if they wouldn't want to admit it because it's not socially acceptable. Otherwise, we probably wouldn't have as much political support as we do for xenophobic social policies in the UK.