Yes and no.
They are as valid or invalid as we make them, at the very least - and a handful of mine simply can't be explained rationally without a spiritual component.
I wish I had a deeper answer than that, but all I can say is that I believe in something outside ourselves that can, for some, to varying degrees of strength and frequency, open them up to things that can be explained only as "spiritual". Again, I know that's the case with a few of my own experiences that were far more than just "valid".
However, I also believe some people simply are not open (or as open) to such experiences, for some reason I just don't understand - and I wish we collectively respected that more in the Church. It's interwoven into various passages and verses in our scriptures (that not all have the same gifts, for example), but we tend to accept the more black-and-white, all-or-nothing verses and ignore the implications of the others. I understand that's human nature, but I wish it wasn't so prevalent.
mormonshorts: In Memoriam
7 hours ago