The idea was to permit Tay to "learn" about the nuances of human conversation by monitoring and interacting with real people online. Unfortunately, it didn't take long for Tay to figure out that Twitter is a towering garbage-fire of awfulness, which resulted in the Twitter bot claiming that "Hitler did nothing wrong," using a wide range of colorful expletives, and encouraging casual drug use. While some of Tay's tweets were "original," in that Tay composed them itself, many were actually the result of the bot's "repeat back to me" function, meaning users could literally make the poor bot say whatever disgusting remarks they wanted.
Pop-culture references to Skynet and a forthcoming "war against the machines" are perhaps a little too common in articles about AI (including this one and Larry's post about Google's RankBrain tech), but they do raise somewhat uncomfortable questions about the unexpected side of developing increasingly sophisticated AI constructs – including seemingly harmless chatbots.
Creating a comprehensive conversational flow chart will feel like the greatest hurdle of the process, but know it's just the beginning. It's the commitment to tweaking and improving in the months and years following that makes a great bot. As Clara de Soto, cofounder of Reply.ai, told VentureBeat, "You're never just 'building a bot' so much as launching a 'conversational strategy' — one that's constantly evolving and being optimized based on how users are actually interacting with it."