There are still a lot of good pills floating around, but the recent trend has been for the sale of Piperazine based pills (usually a combination of BZP and TFMPP) as "ecstasy" due to the legal status of the chemicals and the cheaper, more abundant supply.
I've recently knowingly tried pipe pills just to have a personal experience of them to compare to actual MDMA, and it's as horrible as people say.
A good way to determine whether your E pills are pipes or not is to look at the press, and taste it. (Of course, the best is to use a test kit. Pipes react a certain way to Marquis tests)
Pipes generally come in a very well-pressed round shape, outpressed design, often larger but lighter in weight in comparison to MDMA pills, and have a shiny, waxy appearance. There's also been a big trend where pressers are using novelty presses, like a cutout press shaped in Bart Simpson's head, transformer logo head, etc. Those are all notorious pipe pills.
The physical taste of these pills, and I have tried it out, when you put your tongue on the pill it's almost like putting your tongue to the positive and negative terminals of a 9-volt battery.
It's like half a taste and half an actual reaction to the surface of your tongue. Normal MDMA pills just have a bitter taste, but couldn't be compared to tasting actively acidic.
A good site to refer to when scoping out some pills is
http://www.pillreports.com
Users all over the world take photos of E pills they get, and a lot of them test for chemical content, and write about the quality of the pills. I'd advise anyone considering buying pills to find out the name, color, and press of the pills they're interested in, and searching for them at pillreports.com.
According to that website, there are still very good pills going around. Particularly the Blue Mickeys and the inpressed Glocks (not the revolvers), and although more rare, but unanimously confirmed, are the Mollys, which are capsules containing MDMA powder.
People have gotten pretty good at identifying a chemist/manufacturer by the pill presses he/she uses, and it's usually a very good method of pre-determination, and that's proven by the responses to the press. If you keep up with that site, along with
EcstasyData.org: Ecstasy Lab Testing & Analysis Results - Ecstasy Pill Reports, which is an informative resource for all the pills that have been tested to date, you can really be more in the know and make better decisions if you're going to buy some pills off the streets.
Having some confidence in a drug you're about to take can at least make things a bit safer if you're going to do it.