Coffee – My dad used the tea brewer with coffee and now the plastic makes the tea taste like coffee. Bleach

Caffeine is definitely bitter. About the only thing I know of that can add bitterness or that strong flavor to coffee is roasted chicory. It's a key ingredient in French Market coffee blends, and it makes them taste pretty darn strong, even though they have less caffeine.

You can get roasted chicory by itself at some supermarkets so you can add it to your decaf coffee, but it may be hard to come by in your area. If you can't find that, see if there's a decaf French Market blend. That'll have chicory and may give you back the bitterness you crave.

I think you're probably out of luck on the tea, though. You might just cut well back on the tea and drink regular tea once in a while. A jolt of caffeine now and again won't kill you, and life's too short to drink tasteless tea.

I don't know anything about Illy coffe but you may find these can answer the question I think you are asking. Here is a flavor wheel for coffee: http://www.flickr.com/photos/visualthinkmap/2741624371/ and here is a link and a great website for pretty much everything coffee: http://www.wholelattelove.com/articles/coffee_tasting.cfm.

Also just to be complete here is a direct quote from the site above, Whole Latte Love, about Illy coffee:

"The world’s coffee of choice." Discover the extraordinary pleasure of illy, the celebrated Italian espresso coffee served in the finest restaurants and cafés and enjoyed by coffee connoisseurs worldwide. A blend so popular, it is served in Italy alone over 2 million times a day. Prized for its full, rich body and smooth, balanced flavor, illy's signature blend is meticulously selected and is 100% sustainably grown Arabica coffee. Espresso at it's finest!