Weird responses to craigslist ad that i can't make sense of?

[Adonis]

i have an ad on craigslist - i'm not selling anything - it's in the 'personals' section, and i've gotten a lot of real responses, but i also got 3 different emails that either said 'hi' or 'hello'. literally, that's all they say. the first one i thought was just either shy or someone who doesn't talk much, cuz i know a few people like that, but then a second one came in 2 days day later from a different person. To both of them, I'd said something like "hello to you too; are you interested?" and as you may guess i haven't heard back from them. just now ANOTHER 'hello' showed up in my emails. i know a pattern when i see one, and i wanna see if any other craigslist posters have encountered this. it cant be a scam cuz they are literally just saying hi, but if its not a scam, what is it?