2002 Subaru Forester coolant smell after replacing water pu

In mid December, my temp gauge shot up all the way. My mechanic said it was the water pump. After it was fixed, I smelled a strong coolant smell. They checked it over and said everything was fine. Three weeks later, my temp gauge shot up again. This time, it was the radiator hoses that needed to replaced, which they said were fine when they replaced the water pump. I went two days after the second repair with no coolant smell -- but now it's back. Both my husband and my brother looked for and couldn't find any source of a leak, but could smell it as well. Until now, my car has been very reliable.

1) What could the coolant smell be?
2) Should I continue to trust my mechanic or are they missing things they shouldn't be missing?