Just stumbled over this thread, started more than thirteen years ago, and once again I felt flabbergasted that within a forum devoted to enemas the advocates of such chemical filth are more than an isolated exception. Perhaps the best sentence was written within message #33 by a well known bygone member (skipping the "hard" and "punitive" references for which I'll never have any appreciation); yet as with everything in this world, to each her/his own.
As for novices, a Fleet is the worst way of learning anything good about the cuddling wonders of the enema experience, provided that you aren't in only for the cheap thrill of forcing a bowel movement by having a cup of irritating schmutz linger in your rectal area drawing fluid from your surrounding tissues. I only had one administered in a hospital by doctor's order three days after my emergency appendectomy. I had begun giving myself proper enemas a couple years before and the squeezebottle's effect wasn't anything memorable. It just restarted the bowel functionality following the momentary paralysis induced by anesthesia yet gave me more than a "tingle": it left for hours a distinct, uneasy feeling to the opposite end of my already numb colon. I never had one before, even if I already about knew what it was, and under no circumstances I will take another.
Of course I'm addressing to newbies: I won't even consider trying to convince whoever is into any other standpoints about the subject. To make things clear, mine comes from an individual who has never suffered from constipation, but again whenever in need of a quick relief and the proper equipment cannot be at hand, given one is not ailed by some unusual bowel conditions such as dolichocolon, atonic colon, non-toxic megacolon or the like, you may always follow rollie7's advice about taking advantage of the handy nozzled bottle after discarding its content. Just stay away from laxatives and think about either choosing quality over quantity or putting your daily food / fluid intake back on the right track instead.
Authors of messages #26 and #55 did make the gist of it clear for the innocent. I hope that will help to steer them right... Also I'd like to point out that, given the varying sensitivity of different individuals, what redbaglover said about the nasty aftereffects of a too-strong soapsuds solution, whenever the recipient wouldn't care to take a thorough rinse afterwards, holds true. I'd go further: sooner or later irritation will invariably take its toll on your inner tissues. Thrillseekers and easygoers should remember that your colon is a living thing, not a piece of plumbing. Play safe! The choice between incorporating into your lifestyle something capable of giving it an elating lift and simply messing with yourself for fun, or heavens forbid with a recipient's innards, is yours. For instance, that's why one should rely only on real unadultered castile soaps in liquid form and work up concentration until fully understanding the individual threshold between its 'wetting' (surfactant) action and the irritating one, and stick to the former - always taking a large rinse afterwards with the isotonic solution of choice.
The warm inner embrace of a proper enema is priceless, anything else is not. Of course if the threat of those nasty dry heaves is what you're after, well disregard what I've just said and enjoy your wicked phosphate bombs. To each her/his own - I repeated myself, amen.
Last but not least, take a peek on this:
https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-warns-possible-harm-exceeding-recommended-dose-over-counter-sodium
Just my 2 (€)¢...