Food that makes people sick will often:

Food that makes people sick will often taste the same as normal.

Explanation:

Most of the time foods that can cause disease have a different taste and aroma than normal. This change is a sign that people do not eat this food and do not get into any trouble with them. However, there are foods that are not fit to eat, but do not have a change in taste, ie, these foods can make people sick, but do not taste different than normal, causing people to eat without realizing that they are changed.