IMNSHO, the challenge system we currently have lends quite a bit of thrill to the game. Bluffing is certainly part of it, and anyone can be bluffed, even experts. Try as some experts might to look down on the practice of playing phonies, everyone does at some point. To a certain extent, the knowledge that a certain word IS good is sometimes just as hard to obtain as is the knowledge that it is NOT. That is to say, people have played enough to know the difference and I believe they deserve to benefit from the knowledge.
Phoney-detection strategies are as varied as players. There are a few good tips I would offer anyone, especially beginners. (These are not tailored for you, Jim, although we have played before)
1) There should be no disrespect given for those people who play phonies, although chances are if you want to get better in Scrabble, phonies will succeed less often (against better opp's) and they're less necessary as you learn the real words in the racks you play. They are essentially a crutch. You should use them when you have to. Also, don't be afraid to challenge. If you learn a new word The Hard Way the red X helps it to stick. You can use it to your advantage in some other game.
2) Playing phony 2s,3s, and 4s is a bad idea on someone who is rated higher than you. If you are going to play a phony make it a six, as not even many experts know all sixes. If you are going to do it you should play it just as confidently and quickly as you do another play. It's also said that most phonies are bastard children of two legitimate words, so if you can make this work to your advantage, work it!
3) Holding your opp. on words you're unsure of is free and may make them think twice about playing phonies if they think you may challenge that one or the next one.
4) All sorts of people are under- and overrated. Although some methodically study scrabble lists, some don't and are vulnerable. I know 1700+ players who haven't methodically studied 4s. I know 1000-level players who know their 5-vowel 8s. You never know unless you play someone enough. Make this work to your advantage! Put on your Game Face!
5) Top 100 6-letter roots are good to study because then you can reverse-engineer the letters and see if there is anything in the rack (assuming it is a phony bingo). Even just reading them over (not necessarily drilling them) goes a long way towards challenge-proofing them.
6) Learn the crazy-looking f&*^ed-up words in order to draw the challenge! Beat peeps playing STRONGYL, SMARAGDE, KAMAAINA, and all the rest. The more words you read the better off you'll be.
8) Guard against bad challenges by a) avoiding pronouncing words incorrectly in your head and b) learning parts of speech info. Example: Do not pronounce PREDIAL as [PREE-dial] because of PREDIALS*. The word is [PRAY-dee-uhl] and takes another A for PRAEDIAL, an adjective. SALTIER, on the other hand, should be pronounced [sahl-TEER] and noted for the noun it is, hence -S.
9) Every good player should exploit their opp's weaknesses. We all make strategic decisions and sometimes those pay off. If I put down LEKU hoping my opp. will S-hook it so I can challenge off LEKUS*, is this relying on their weaknesses? Hells yes! If I feel comfortable in later S-hooking it and then my opp. accepts, is that taking advantage of their weakness too? Yep. We're expected to play our best games, and that includes playing the player, not just the game.