PI puts up a "facade" of great research, but doesn't support real academic work. Is this common? How to recognize this kind of situation?
In this question, I see two separate issues: First, you have the impression that you fell for someone similar to an "academic con-artist". Second, there is a conflict of goals between you and your supervisor. Your question is worded in a way that emphasizes the first issue, but in this answer, I want to make the point that it would be more productive to focus on the second issue.

Let me summarize the situation from my perspective. Your goal is to make an academic career, and for this goal you (reasonably) strive to produce work that gets published at top-level conferences. Your supervisor's goal, however, is to establish a new research direction which may or may not ever pan out to be of interest to top-level conferences. Since these conflicting goals seem impossible to reconcile, it is clear that you need to change your supervisor.

Since you don't want to wind up in the same situation again, you're wise to ask how can avoid that in the future. By focusing on your goals, this question becomes almost self-answering: Choose an advisor whose goals are easier to align with yours. The ideal advisor would be one who lets you work on a topic where he has recently published papers in top-level conferences.