If you eat bad vegetables you will likely get sick and suffer stomach pain, diarrhea etc.
I have accidentally eaten bad vegetables and I got stomach pain and diarrhea and bloating that went away within a few days.
I had some vegetables that I had leftover in a can that I put in the refrigerator in a sealed container and they were left in the refrigerator for 7 days.
The vegetables smelt okay and tasted okay and had no mold but I guess they were bad because I got sick about 4 hours after eating them.
I thought I might have gotten really bad food poisoning at first so I went to a walk in clinic and they said that it was not direct food poisoning but that the old vegetables just made me sick and I should get feeling better within a few days or so.
If you have vegetables that have been stored in the refrigerator longer than 3 or 4 days then it's likely bad and should be thrown out.
Vegetables that are not canned vegetables such as potatoes, tomatoes etc should last for a few weeks out on the counter.
When the vegetables go bad you'll usually notice a change in texture, color and smell of the vegetables.