An unpleasant soil smell can be due to anaerobic conditions (low oxygen due to compaction, excessive wetness, or anything else blocking enough oxygen from entering the soil). Some soil testing labs can screen for certain heavy metals (often lead at the very least, regarding vegetable gardening concerns), and you can use the lab list on the linked page to find a lab to submit a sample to. They cannot screen for toxins like pesticide residue, though we would not expect that to be the case in this situation. If the soil smelled a bit like manure, maybe the soil source had been mixed with (or originated from) a site that composted fresh manure.

Miri