Depends what you're trying to look at. If you're trying to show the presence or absence of distortions, then a frequency display is the obvious thing - you would be looking for clean transmission of signals of multiple frequencies without any distortion products (i.e. harmonics - at multiples of the input frequencies - or intermodulation products - at sums and differences of the input signals).

Beats are not necessarily indicative of distortions - just multiple frequencies in the signal.

I'm assuming you're not talking about "beat" as in "rhythm" and our perception of it (although a frequency display can be useful in looking at irregularities in a repetitive sequence, as in "jitter spectrum"  ) - there you're probably best off looking in the time domain: check out the rise and fall times of the signal envelope.

Looking at signals on a scope can be quite artistically moving - just like watching a dancing flame - but whenever I get to do so its a) much higher frequency (RF) so there's no associated physical experience and b) it's all tightly time-synced so we really don't want any irregularities at all (as that shows its "broken"  )