There are two types of people in this world: people who text you back right away, and people who might take hours (or even days) to reply to your messages. Tardy texters don't usually mean to be rude — they're just easily distractible, or way too freaking busy, or so indecisive that it takes them several hours to come up with a response. For zodiac signs who don't text back right away, timely replies simply aren't a priority. It's not you, it's them (and their totally inability to text their boo back in a reasonable amount of time).
As a Scorpio, you can usually assume that, if I haven't texted you back within 10 minutes, I'm either asleep or have fallen off the face of the earth. Scorpios are deeply intuitive and sensitive people who hate staring at a blank screen waiting for a reply, and I wouldn't put my worst enemy through that kind of agony. (Did I mention that Scorpios are also a bit dramatic?) But for those zodiac signs who tend to leave their SO on "read," texting back doesn't have the same kind of urgency. If you text these six signs, I probably wouldn't expect an immediate response.