As mentioned, it is at low level on approach I get concerned and lacking in confidence. Example. Going into Gerona RW02 approaching from the east 4000'. ATC is giving CB's in the vicinity. There are hills directly west of the airfield within 10nm and mountains to the north. We spent a lot of time painting the area during descent and 25,000-15000' it seemed not too bad a prospect. We asked BCN for some radar Wx advice. Useless, and GRO didn't have any. It was daylight and it didn't seem too back and ugly. We proceeded to 4000' and were now looking at the hills. The deep red covered the airfield environment as well. We couldn't get rid of it. To venture in or divert? It still didn't look dark enough in the cloud to cause those tomatoes. In the end it was only heavy rain and a few bumps. We'd asked ATC about conditions over the airfield, cloud base, w/v, rain etc. and it seemed very doable. We were coming in over the sea and the wind was slightly NE pushing the clouds further inland.
With no outside information the radar gave us a No-Go picture. It is something I never managed to work out over 25 years of colour displays; how to achieve accurate low level returns with confidence.