Yes, the sentence is grammatically correct. It conveys a clear message, but it can be rephrased for clarity or style if desired. Here are a few alternatives:
1. "Have you ever experienced this? I was told that it signifies a sign and a bad omen."
2. "Have you ever gone through this? I understood that this indicates a sign and a bad omen."
3. "Have you ever encountered this? I was meant to believe that this is a sign and a bad omen."
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