Cook pasta in salted boiling water until al dente, then drain and rinse briefly with cool water.
Cool pasta completely in a large bowl, then add corn, black beans, bell pepper, tomatoes, red onion, cilantro, and chicken if using.
Whisk mayonnaise, sour cream or yogurt, lime juice, chipotle, garlic powder, onion powder, cumin, smoked paprika, salt, and pepper until smooth.
Pour most of the dressing over the pasta mixture and toss gently to coat. Add remaining dressing only if needed.
Chill for at least 30 minutes, then taste and adjust seasoning with extra lime, salt, or cilantro before serving.
