I love using old containers too, but you have to use a hard brush/diluted bleach when you're cleaning most of them. Did you by chance add drainage holes to the bottom of your containers after cleaning? They can make almost any container livable.

I frequently repurpose old deli and yogurt containers. As long as they have been throughly cleaned, they work fine. A trip through the dishwasher does the trick as well. In both cases (this and the bleach routine Marina mentioned,) be sure to rinse the containers afterwards to remove any detergent or bleach residue.

I am going to take a second look at 3 one ounce Solo cups I was planning on reusing.

Nothing wrong with reusing containers. Just make sure you wash them in hot soapy bleach water and rinse well. Rosie

yup! Residue is The Enemy. :o)