Someone who regularly samples my creations said they didn't much care for beers with an ABV of less than 5% as they're "a bit watery and tasteless". Not normally a problem as most of my beers have been in the 6% region, but I've recently been drinking a batch that I deliberately brewed well short of my normal strength that came out at 4.2% abv. The 4.2% bitter has a nice whack of hop flavour up front (25 IBU), followed by a malty sweetness, medium mouthfeel - it's a good beer. Having said that, it dawned on me that the one flavour component that was missing was the alcohol you'd normally pick up in stronger beers. Hop, malt and carbonation effervescence are all there - can't help but wonder whether the same recipe bumped up to 5% would take it to the next level. I'm guessing that the perceived alcohol taste is relative to IBU (ABV and IBU are related in recipe builder...) but is there a guideline level at which we'd expect to pick up an alcohol taste?