I avoid 3 word domains unless two of the words are related in such a fashion where omitting one would destroy the meaning. For example UsedRecordSwap.com might be an alternative to RecordSwap.com since a "used record swap" has a somewhat obvious meaning of swapping old vinyl records, whereas "record swap" could mean swapping anything considered a "record" such as a birth certificate, especially to anyone under 40 since many wouldn't have ever owned vinyl.
The difference is subtle.
Craig