I wouldn’t respond at all to anyone you are not interested in meeting. Since many don’t respond to messages unless there is interest, simply replying— even if it’s to say you’re not interested— is interpreted as an opening. Even with the guy texting you wyd, the fact that you even said “no” is probably being read as “not this time, maybe next time.” Responding to people you aren’t interested in is also a drain on your time. When I did online dating, I just didn’t respond to anyone who I wasn’t interested in. Even if they messaged me through the site multiple times, I just deleted the messages unread. They eventually took the hint and saved me time & energy.