So basically you will never get blue ticks from them.
I know a few people who do this and it really annoys me because I now assume they've seen it but don't rant to reply. I keep my ticks on because sometimes I'm not able to check my phone frequently. I'd rather someone know I haven't seen their message yet, not that I'm ignoring them, or maybe I have seen it and just forgotten to reply - so they can prompt me.
I find it weirdly controlling that someone doesn't want me know they've read my message. Of course, you don't know when an email has been read, or a phone message listened to, but WhatsApp has that function which I think is great.
If you're someone who turns off the blue ticks, can you tell me why...