As a general rule, symptoms related to cultural stress factors are going to show up in the lighter areas of variegation on variegated plants. Karen is right in that there is not enough info, but the usual suspects when it comes to spider plants are A) over-watering, potentially exacerbated by an inappropriately water-retentive medium, B) a high level of dissolved solids (salts) in the soil solution, or C) fluoride toxicity. Something I wrote about their cultural wants: While necrotic leaf tips or margins can occur in this plant from over/under-watering, in fact, it's also very common for the actual cause to be a high level of soluble salts in soils. It's also habitually reported that this plant is particularly intolerant or fluoride, but it's still more common for the cause of leaf burn to be a high level of solubles, to which fluoride can be a contributor, than it is to be fluoride itself. WHEN there is a high level of salts in the soil, low humidity can be a contributor, but low humidity alone rarely presents an issue, it must be in combination with a high level of soluble salts in the soil or either over/under-watering. Of course, you cannot correct the already burned leaf tips and margins (they won't 'heal'), but you can take steps to keep it from happening: A) Most important is to use a soil that drains very freely. This allows you to water copiously, flushing the accumulating salts from the soil each time you water. B) Fertilize frequently when the plant is growing well, but at low doses - perhaps 1/4 the recommended strength. This, in combination with the favorable watering habit described above, will keep soluble salts levels low, and keep levels from rising due to the accumulative effect we always see when we are forced to water in sips when plants are in water-retentive soils. C) When watering, using rainwater, snow melt, water from your dehumidifiers, or distilled water also eliminates the soluble salts in your tap water and will go a long way toward eliminating or minimizing leaf burn. D) If you make your own soils and use perlite, be sure the perlite is rinsed thoroughly, which removes most of the fluorides associated with it's use. E) Allowing water to rest overnight doesn't/won’t do anything in the way of helping reduce the amount of fluoride (the compounds are not volatile), and it only helps with chlorine in a very few cases, depending on what method of chlorination was used to treat your tap water; but nearly all municipalities are currently using chlorination compounds that are entirely nonvolatile, which means they won’t dissipate into the air. Al

Remove the dead and dying leaves. Overall it looks fine unless you can post photos of the new leaves showing a major problem. Was the residue there when you bought it? I see a lot of plants from Florida (Home Depot and the like) where the plants were treated before shipping. Usually a wet sponge/paper towel can remove most of the residue. Leaving it in a shower without enough light is not good for it. It was enough shock for it being shipped hundreds of miles to live in a home when it was nice and happy growing in a commercial greenhouse.

Any sticky reside (honeydew) on lower leaves or the floor? Do you know how to test for spider mites? What are you fertilizing with? How long have you had it, and, have you ever done a full repot, and what kind of soil is it in. In order for new leaves to form normally, Ca(lcium) must be in the nutrient stream at all times. If the plant is not taking up enough Ca, or the flow of the nutrient stream is disrupted, new leaves emerge deformed, often with brown margins which turn necrotic with the necrosis extending inward. Your plant presents classic symptoms. The question is, is the deficiency caused by an actual deficiency where there is not enough Ca in the soil, or, is a cultural influence (over-watering, soil compaction, an excessive amount of Mg (magnesium) in the soil, a pH issue, ....? Low light, cool temperatures, high humidity also slow respiration which slows the nutrient stream which limits Ca availability which exacerbates manifestations of the deficiency - the malformed leaves. You don't offer enough info so I can't say what caused it to occur, but look first to over-watering. Going only by the odds, that's the probable cause. Al

@SylviaWW 9a Hot dry SoCal in hot conditions where the sun is brutal, any distance you can put between the physical plant tissues and the hot, reflective, heat-radiating wall surfaces will help. Allowing air circulation behind the roses, between them and the wall will not only help to permit the heat to dissipate, but will also reduce the amount of water stress caused by the hot wall literally cooking the moisture out of the roses. The hotter it is, the more they sweat (transpire) and you can literally force them to contract fungal issues, most notably rust and mildew, from severely water stressing them. Growing grass around them will increase the possibilities of water stress as the turf competes with them for water. The rose feeder roots will grow within the top few inches of soil and that's where the grass roots are. Ideally, there wouldn't have to be lawn around them, only a deep organic mulch to keep the soil moist and cool. But, the reality is, you have to do, what you have to do. Good luck!