Could be bad seed, but sounds like a soil problem. It almost sounds like too much fertilizer in the soil or the soil is too wet/retentive. Some plants are more sensitive to soggy soil and fertilizer then others. You can transplant very young seedlings if you are very careful. I'd transplant them, and try some more. Make sure you have a good soil less mix to start them in and don't feed or overwater them. Seeds like damp, not wet soil. It's hard to figure out exactly whats happening without more info or pics.

Before you plant new ones, let's find out what the problem is with these: you don't want a second batch of equally unhappy seedlings.

What planting medium are you using? How do you water, and how often? Where are the seedlings growing, and what is the temperature? What's the lighting?

Using jiffy organic seed starting mix.

Seeds are on sun porch under 4 T8 bulbs Approx 3 inches away from tops. Door to sun porch is left open, it might get down to 55-60 at night but gets warm during the days, 70-80 degrees. I water them when they look dry on the top of the seed starting mix. They are in flats, so I just bring them in the kitchen, hit them with the sprayer nozzle till the mix is wet and then put them back under the lights. Lights are on when I wake up around 7:00 and off when I go to bed, between 9:00 and 10:30 depending on the day. Under the 4 T8 bulbs I also have iceburg lettuce, onions, bell peppers and brocolli starting. They all look pretty normal to me at this point.

Ok. First of all, organic seed mixes are usually VERY water retentive. They are much more difficult to work with then a soil less mix. You will need to to be very careful not to over water them. Make sure soil is not soppy or saturated. Although seeds need moist (not wet) soil on top, once they pop, you need to let the soil dry out more. Secondly, seeds seem to like consistent temperatures to germinate usually around 70F for tomatoes. You may also want to raise your lights a bit more for sprouts. Older seedlings are more tolerant to close lighting.

See if this works, pictures of what I am talking about.

I can see the pictures fine. The funny thing about cotyledons is that they act different from other leaves due to the fact they are not true leaves but storehouses that feed the growth of the rest of the plant, so they will always decline. That being said, I am concerned about the lack of true leaves. Other then that, the stems look ok. I would suggest you just cut back on the watering and see what happens. Don't give any fertilization until they are much larger.