Unclear when scrolling/refresh rate issue?

[Shyfe]

I just exchanged my iPhone and got a refurbished one, which is cosmetically almost perfect, but I'm a bit concerned about the screen. It is slightly yellow, which I've learned to get over, but my main concern is what seems to be the refresh rate. When scrolling while reading text, it the text seems to get thinner/more unclear than some other iPhone screens I've seen like the model ones they have at the store. You can also see some faint horizontal lines if you look closely when it is on a black background and there is horizontal lines on the icons when you scroll left and right. I was wondering if this is just the way all screens are now or if they will exchange it for me if I cite this as the reason. Thanks for reading.