She's right about the tupperware... My mom gave me some she's had since her wedding (1968) and it looks and smells brand new. The new "disposable" ones are the worst at staining with pasta sauce and smelling like the last thing in them. They only sell it at those silly parties like Pampered Chef, but you can get it at used stores all over. That is, if you're in the US, it doesn't say on your thingy.
Here's some random suggestions I found:
# Newspaper/Charcoal: This is the classic method of combating odors. Crumple up newspaper, sprinkle it lightly with water, place in sealed container and leave it for a day. The charcoal in the newsprint will absorb odors. Putting a piece of charcoal, such as what you'd use for a BBQ, in a sealed container also works.
# Baking Soda: There are a couple methods here.
a) Put baking soda in the container and shake, leave it for a couple hours/days . . . .
b) Make a paste of baking soda and water and let it set. After letting it sit, then rinse with water and wash normally. Repeat as necessary.
# Alternative methods:
a) Place the container upside down on the grass outside.
b) After making coffee, put used grounds in container and let set. Some folks recommend drying the grounds first but I found it worked when they were wet.
c) Try rinsing it with lemon juice and then wash it as usual.
d) Put a crumpled paper towel in a sealed container with a bit of kitchen cooking vanilla on it. Some folks even keep containers such as thermoses, coolers, etc., stored tightly closed in the garage with a vanilla paper towel and it seems to work well.