Cognitive Radio has a potential to improve spectrum efficiency for future wireless communication systems. However, the performance of such systems can be degraded by various factors e.g. imperfect sensing, non-accurate result reporting of the sensed spectrum either due to error-prone reporting channel (RC) or malicious user attack. Moreover the phenomena of reporting only from those cognitive users (CUs) whom RC is above a pre-defined threshold, can help in improving the throughput for the cognitive radio system (CRS). In this paper a detailed study of the aforementioned reporting mechanism with respect to sensing efficiency has been formulated to analyze the impact on CRS performance. Furthermore, to filter the inaccurate information which tends to increase the miss detection probability we propose an effective cooperative spectrum sensing (ECSS) algorithm via a two-level eligibility cooperating criteria. Simulation result shows the effectiveness of the proposed methodology.