You can clean the wood with a damp cloth and some mild soap, let dry and treat the wood finish as you would your other pieces,The chair could be washed on the delicate cycle of your washer and hung dryed, no dryer.
Stainless steal is easy to clean but can get messy again easy.
Any table that has a topcoat of finish should be very easy to clean just by wiping. Card tables are very difficult to clean, however.
Flat keyboards are easier to clean, but they may be a bit more difficult to use. Flexible keyboards, which are very easy to clean, are also becoming available on the market.
Depending on the type of furniture the cleaning difficulty and range from medium to hard. If the furniture is laminated wood it will be fairly easy to keep clean. But is the furniture is stained it will be a lot more difficult to clean and maintain.
If you have a high quality leather then it should be easy to clean. A lower quality leathers might be difficult to clean. In either case white leather is going to show dirt more easily and will require regular cleaning.
Yes, dry erase calendars are easy to wipe clean. If marker is left on the calender, it dries onto it and is slightly more difficult to remove, but still is possible by rewetting it with another marker.
I have not used any of George Foreman's grills but considering their description where some of the parts are removable, we could probably assume that it is as easy (if not easier) to clean as similar products.
Downdraft cooktops are no more difficult to clean or keep clean than regular cooktops. The flat surface can cause food to get burned to the surface. It is best to use a razor vlade very carefully to remove the food.
Sony headphones are very easy to clean because the material easy cleans.
difficult
There are many products available to help you clean your leather couch. Leather couches are not any more difficult to clean than suede couches. You will need to buy a leather conditioner to keep it in good condition though.
water is easy to clean because it does not stick or stain.