The scary thing is that yea we can see these in 2D and maybe 3D. But ...

usually there are more than 2 or 3 columns in our data :(

It's clearly hard, but there are tools for doing exploratory visualization of high-dim data. GGobi http://ggobi.org/ and all the ones that arrange points but try to get local neighborhoods correct (t-sne, umap, et al.).

	▲	lamename 5 days ago \| parent [-]
		Yeah, but still "scary" because you have to be really careful to not fool yourself and pay attention even with those algorithms. For example, a good demonstration with tsne https://distill.pub/2016/misread-tsne/?hl=cs