I followed someone's suggestion and went to check on my plants after dark. I found one snail on the side of my raised bed (it has tomatoes, peppers, eggplants in it), and bunch of snails in this one and other bed (that has lettuce, cabbage, cucumbers, zucchinis, onions, carrot, sugar snap peas). Most snails were very interested in the marigolds in the tomatoe/eggplant bed, and also liked my cabbage and lettuce (none of the other plants in that bed). The eggplants have leaf damage but different pattern (tiny yellow dots) and I found out it was caused by black flies (small tiny round black insects) and I treated the bed with Sevin and they seem to have left. The bed that has marigolds does not show any signs of leaf damage on any plants (tomatoes, eggplants (besides the flies), peppers). The cabbage/lettuce bed does not have marigolds. I also saw one spider and few spider threats holding some tiny white round insects -- I guess he got himself a meal and built a house on the cabbage leaves.

So now I am wondering - are slugs and snails known to eat marigolds and don't touch other nearby plants? Should I plant marigolds in all beds and be happy that slugs eat them and not my plants? Should I still treat all beds with - what? - Sluggo? any other pesticide? I don't care if it's organic or not, but something that can be washed away.