Guttation is a watering problem - droplets of sticky moisture appear on uninjured leaves as a result of too much soil moisture and too much humidity in the air. Moisture is not lost as quickly through evaporation in very humid air as is being absorbed by the roots, so it oozes out of plant pores. It is often seen as a sugary-looking crystal at the base of a leaf of a weeping fig and assumed to be an insect.

Jottle, First, your plant isn't D. reflexa/Song of India, however it is a striped Dracaena. There are several reasons leaf spot can develop on Dracaenas including fungal disease, bacteria, insects, too much humidity, and improper growing conditions. How much light is it getting? What about fertilizer? How often? Is it enclosed among other plants? It's possible you've over-fertilized. If over-fertilizing is the problem, you should either repot in fresh, well-draining soil, or leach soil. Do you see clear crystals forming on soil or inner pot? Some Dracaenas dote on humidity, others need a little. As long as there's good air circulation, high humidity shouldn't be a problem. You said you let soil dry...did you test the center and rootball bottom? Soil can look/feel dry on top, but if soil isn't well-draining, center and bottom soil might be wet. Dracaena's need medium light..Direct summer sun can cause spotting. In case your Dracaena has disease or pests, 'I doubt the problem is insects,' isolate. I'd remove leaves with brown spots. Leaves with brown tips can be trimmed, but leave about 1/8" of brown on each leaf tip. How long have you been watering with room-temp water? I'd avoid fertilizing. There's a product I use called SuperThrive. Some, believe it a snake oil, lol, but I think it does wonders. Just my opinion. 10 drops per gallon of water. Good luck, Toni

Looks like Dracaena sanderiana (aka Heavenly Bamboo).

What is in a pot does not matter, as long as it's not toxic to the plant in some way, just its' texture & ability to retain moisture & oxygen @ the same time. If it has no inherent fertility, very effective fertilizers exist to serve those needs. I don't doubt you at all. I don't have access to ingredients for that so I can't offer any feedback about it. If buying a bag, I look for cactus/palm soil, but go more by weight over what it says, and look for a broke bag to inspect and make sure there's no peat in it, and hopefully not much perlite. If it's not lightweight for its' size, it's not helping me reduce the weight of larger pots, and probably not going to help with keeping more oxygen in the soil. Digression alert, probably on this whole post... I don't want to be confusing either, and do not offer any of this as a recommendation because it has evolved over quite some time of trial'n'error, and other, personal factors like personal acute dislike of perlite & seeing those little white things in my pots, a lot of reading about roots & microbiology, dislike of spending much $ to have something in a pot in which a plant can grow, realizing that if there is no peat, I can probably keep a plant alive, ...and especially to someone in the middle of a city without a yard. I'll use anything but peat/potting soil, and often add some roughage from compost pile. Dracaenas grow fine in ground dirt from the "good dirt" part of a tended plot, especially if I'm going to repot them often anyway. Fine for smaller plants but way too heavy for a plant of decent size. Since all old "dirt" gets put into flower beds, I don't put anything in pots that I wouldn't put in/on the ground. This is why I quit buying flats of annuals to use in the ground and started putting my house plants instead, because I kept finding styrofoam instead of perlite in the soil of them. I refuse to bury other people's non-biodegradable trash in my yard.