Jimmy, The symptoms you've mentioned ALL seem to me, to be from over-watering.
Which, no... doesn't mean "watering every day", but rather, keeping certain plants wetter than they can handle & not giving them a chance to "rest" between drinks! (If your humidity is high, they ARE getting SOME water!)
It sounds as though you're going to HAVE TO get those plants out of the soil that's keeping those roots too wet, or I'm afraid that you could wind up with root rot! Get some rocks in the bottoms of those pots (at
least 2 inches) & get them in a light soil that doesn't hold water well. (If you can make a mud ball out of the soil, you'll know that it's too dense to drain properly, for those types of plants.)
I really don't know what to tell you about the symptoms of over-under watering not showing up for a while... it's probably different with each plant type, & you really have to analyze each of them, individually. Let me do some hunting & see what I can come up with for you, & hopefully, some of the people around here who actually have more experience with the particular plants you have, will pop in & tell us what works for them.
Meanwhile, go next door here, & read what I wrote about my
Dracaena . (Be sure to read the archive link there, too. It was VERY helpful to me, in understanding that plant!)
By the way....
The thing I love about these sites with advice for taking care of your plants...
I know exactly what you mean,
But... I would like to think that THIS is
NOT just "one of these sites"!
Just keep asking questions, & if that same person doesn't come back & say more, then someone else is bound to come along who can and will explain things better!
The people here on the Garden Forum aren't perfect, but they ARE the best bunch going! Stick around, my friend, & you'll see!
We DO want you be a successful gardener, & to be able to enjoy your healthy plants!