Answer: Without seeing the damage, I can't really diagnose it, but I can give you a few likely causes:
Spots on hosta leaves can be caused by damage from misdirected chemical garden sprays and other air-borne pollutants. Pinhead-sized brown spots sometimes seen on leaves in late spring and early summer are caused by the leaf-cells bursting due to slight frosts which often occur some time after the leaves have unfurled, and this damage is not apparent immediately. Leaf scorch, similar to leaf spotting, is harmless though unsightly, and is caused by small drops of cold water falling on to leaves growing in strong sunlight. A final consideration: fungal leaf spot, which is caused by the fungi Alternaria, can be controlled a fungicide.
Hope this information helps you determine just what the problem might be.
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