Honestly, it's entirely up to you. If a loop or patch fits your track, just say "fuck it" and go for it. And IMO, there's nothing wrong with you using a sample or patch if it fits properly, and why wouldn't you send it to a label? The sample you purchased is cleared and if it makes your tune bang, I don't see the problem. Also, even if you start a track with a sample and build it around that sample, there's no reason you can't simply take it out later if your tune stands its ground on its on.
I can see how people may perceive the use of samples and loops as "cheating," but I call bullshit on that for two reasons: The first is that even if you have a track laid out with all purchased samples and what not, it's still going to take some skill -- skill to EQ all those sounds, skill to get them to fit together nicely, and most of all skill to make sure the arrangement is banging. The second reason is a bit of a metaphor: Producers are essentially chefs, and just because you have all the ingredients in front of you doesn't mean you'll automatically be able to create a 5 star meal. What good are those ingredients if you don't know how to use them to their full potential and/or make them taste good for that matter?
Personally, I dabble in both original loops/beats and sample-purchased. If I've purchased them, I usually chop them up, rearrange them, run them through a filter etc. just to add my own bit of flavor...except with drums. I may start with a break loop sample as a reference but then I build the kits from the ground up. Later on I'll take some break loops and EQ the hell out of them just to add them to my drums to add some drive to the kit. I'm all about total control and usually I'll strip the samples as much as possible so I have maximum flexibility with them. Hell, sometimes I'll even throw them in the old EXS24 and see what happens with a bit of modulation crazyness.
In closing (and to end this long winded post of mine) here are some examples of big producers who have used samples from packs. Tantrum Desire's song "Reach" uses the "Reach Up" vocal from the Zero-G Vocal Forge sample pack. Drumsound & Bassline Smith's "Freak" uses a couple FX loops from a Wave Alchemy FX pack...and I know this because I own both and was enlightened when I heard them in my DAW audio preview area. And then there are Vengeance packs...just skimming through the loops (found usually in the "special sounds folder") in the packs will cause you to take a second listen to some of the sounds and realize "Holy shit, I've heard this sample on so and so's track!" You'd be surprised how many you'd come across, especially in Vengeance Essential House Vol. 2.
Of course this is all in my humble opinion.
Cheers!