especially when you're talking about one liner posts, you'll likely not figure out if it's a bot without other information like IP, any header data you can grab, referrer, etc...
From what I've read about bots, they tend to mix things up so the only thing that may be consistent for a basic bot could be the IP. The referrer and other data would change where an actual surfer it's more likely to remain the same since most people use one browser for most of their surfing and don't change their settings often.
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